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Failure analysis (FA) becomes increasingly crucial for semiconductor industries with the scale-down and larger integration of devices. In order to overcome the limitation of traditional optical resolution for FA techniques, this article proposed an effective method of precise positioning of circuit defect based on localized probing technique, nano-probing and electron beam absorbed current (EBAC). Open circuit, short circuit and gate/capacitor oxide defects were the most common failures in IC manufactures, therefore representative examples based on these failures were employed to illustrate the analysis procedure and effectiveness of the proposed method. Scanning electron microscope (SEM), focused ion beam (FIB) and transmission electron microscope (TEM) results were presented to verify the accuracy of the positioning. It was demonstrated that the proposed precise positioning method was able to accurately locate the defect position, and was useful for determining the failure mechanism as well. The method showed great potential for improving the success rate of FA for semiconductor devices.

A novel method of fabricating flexible thin-film transistor based on single-crystalline Si nanomembrane (SiNM) with high-k Nb2O5–Bi2O3–MgO (BMN) ceramic gate dielectric on a plastic substrate is demonstrated in this paper. SiNMs are successfully transferred to a flexible polyethylene terephthalate substrate, which has been plated with indium-tin-oxide (ITO) conductive layer and high-k BMN ceramic gate dielectric layer by room-temperature magnetron sputtering. The BMN ceramic gate dielectric layer demonstrates as high as ∼109 dielectric constant, with only dozens of pA current leakage. The Si–BMN–ITO heterostructure has only ∼nA leakage current at the applied voltage of 3 V. The transistor is shown to work at a high current on/off ratio of above 104, and the threshold voltage is ∼1.3 V, with over 200 cm2/(V s) effective channel electron mobility. Bending tests have been conducted and show that the flexible transistors have good tolerance on mechanical bending strains. These characteristics indicate that th...

Linearity characteristics of common-emitter (CE) and common-base (CB) configuration SiGe HBTs are analyzed and compared under different matching, bias and frequency conditions. Impedance matching is demonstrated to have significant effect on the configuration-dependent linearity characteristics. Moreover, with source and load impedance matched for maximum output power, CE and CB configurations not only show different power gain relation but also different linearity characteristics dependence on frequency. Theoretical expressions show good agreement of the RF linearity property for simulation and experimental results. Further dc bias study reveals that both higher power-gain and better linearity can be obtained from the CB than the CE configuration under certain bias and operation conditions. A potential tradeoff between the two configurations in terms of linearity and power gain is also demonstrated.

In order to obtain three-dimensional data of engine cylinder head blank, a passive line structured light system with camera coordinates as the measurement coordinates is designed in this paper. Data in different local coordinates can be converted to a global coordinate system, by calculating the camera moving distance and cosines of the moving direction. In addition, the direction cosine of the camera optical center movement is calibrated based on the principle of virtual stereo vision. The virtual stereo vision system consists of a camera moving along a one-dimension guide rail. The cosines calibration method has three major steps: (1) The rotation matrix R and translation vector T from local coordinate to global coordinate system are calculated by stereo calibration. (2) The origin of the local coordinate system is converted to the global coordinate system. (3) The camera movement along the guide rail is fitted and its direction cosine is calculated. By measuring the high-precision calibration board, the designed system demonstrates a higher accuracy of profiling the geometry structure. An engine cylinder head blank is then scanned using the designed system. The three-dimensional data are analyzed by reverse engineering software and the profile is reconstructed well.

The radio frequency (RF) characteristics of proton irradiated large-area silicon–germanium (SiGe) heterojunction bipolar transistors (HBTs) at extreme temperatures (liquid nitrogen temperature of 77 K and high temperature of ∼430 K) are reported in this work. Large emitter area high-power SiGe HBTs fabricated in a commercial BiCMOS process were irradiated with proton, at various fluences from 1 × 1012 p/cm2 to 5 × 1013 p/cm2. Small-signal ac experimental characterizations were achieved for pre- and post-radiation devices at room temperature, cryogenic and high temperatures. We show that proton radiated large-area SiGe HBTs are naturally suitable for electronic operations at extreme temperatures. Investigation of proton radiation on large-area SiGe HBTs at liquid nitrogen temperature (77 K) demonstrates great potential of SiGe power HBTs for space applications. Moreover, performance of proton radiated SiGe power HBTs at high temperature of ∼430 K indicates a better tolerance of proton radiation than room temperature. Possible underlying mechanisms for the improvement of radiation robustness at cryogenic and high temperatures are discussed. The results demonstrate the possibility of using large-area SiGe HBTs in power amplification for wireless applications under severe radiation and extreme temperature environment without any intentional radiation hardening.

Traditional flexible electronics employ amorphous Si, poly Si and organic materials, but these materials cannot be used for fast (radio-frequency, RF) flexible electronics due to their low carrier mobilities. Instead, we employ monocrystalline Si as the active materials. These high quality materials were released from silicon-on-insulator by undercutting the buried oxide layer. They have equivalent mobility values as their bulk counterpart, yet with high mechanical flexibility. We realized the first RF flexible thin-film transistors by performing pre-release doping and changing the transistor fabrication process to gate-after-source/drain to avoid high temperature process on plastic substrate and achieve low source/drain contact resistance. We further increased the device speed with reduced source/drain access resistance through careful device structure design. By realizing smaller feature size (1µm) with local gate alignment and higher fidelity membrane registration/transfer technique, 12 GHz flexible thin-film transistors were demonstrated. Strained channel and nanolithography are projected to further increase device speed.

This paper reports the realization and RF modeling of flexible microwave P-type-Intrinsic-N-type (PIN) diodes using transferrable single-crystalline Si nanomembranes (SiNMs) that are monolithically integrated on low-cost, flexible plastic substrates. With high-energy, high-dose ion implantation and high-temperature annealing before nanomembrane release and transfer process, the parasitic parameters (i.e. resistance, inductance, etc.) are effectively reduced, and the flexible PIN diodes achieve good high-frequency response. With consideration of the flexible device fabrication, structure and layout configuration, a RF model of the microwave single-crystalline Si nanomembrane PIN diodes on plastic substrate is presented. The RF/microwave equivalent circuit model achieves good agreement with the experimental results of the single-crystalline SiNM PIN diodes with different diode areas, and reveals the most influential factors to flexible diode characteristics. The study provides guidelines for properly designing and using single-crystalline SiNMs for flexible RF/microwave diodes and demonstrates the great possibility of flexible monolithic microwave integrated systems.

Multigigahertz flexible electronics are attractive and have broad applications. A gate-after-source/drain fabrication process using preselectively doped single-crystal silicon nanomembranes (SiNM) is an effective approach to realizing high device speed. However, further downscaling this approach has become difficult in lithography alignment. In this full paper, a local alignment scheme in combination with more accurate SiNM transfer measures for minimizing alignment errors is reported. By realizing 1 μm channel alignment for the SiNMs on a soft plastic substrate, thin-film transistors with a record speed of 12 GHz maximum oscillation frequency are demonstrated. These results indicate the great potential of properly processed SiNMs for high-performance flexible electronics.

This paper discusses the impact of transistor performance and operating frequency on the design of monolithic highly efficient RF SiGe power amplifiers (PAs) using on-chip lump-element passives and/or bondwires to approximate the class E switching conditions. Single-stage SiGe PAs were designed and fabricated using both high-breakdown and high- fT devices targeting for the highest power-added-efficiency (PAE). The PAs designed using high-breakdown devices with on-chip tank inductors exhibit similar gain and PAE as those of high-fT devices, but capable of withstanding significantly higher supply voltages and deliver larger output power (> 23 dBm) more reliably. PAE of 68% (900 MHz) and 40% (2.4 GHz) was achieved from these highly integrated suboptimal PAs without using any off-chip matching. The degraded PAE at 2.4 GHz versus 900 MHz is shown to be caused by increased effective ground inductance parasitics, higher loss from both low-Q on-chip tank inductor and increased SiGe device switching loss with reduced power gain. Design insights on how to improve PAE of SiGe PAs at higher RF frequencies are discussed, as we increased the measured PAE of the class E PAs to an impressive 62-65% range at 2.3-2.4 GHz, which is among the best reported in the literature for Si-based monolithic PAs.

This paper provides a review of the recent developments of self-organized In(Ga)As/Ga(Al)As quantum dot lasers grown directly on Si, as well as their on-chip integration with Si waveguides and quantum-well electroabsorption modulators. A novel dislocation reduction technique, with the incorporation of self-organized In(Ga,Al)As quantum dots as highly effective three-dimensional dislocation filters, has been developed to overcome issues associated with the material incompatibility between III-V materials and Si. With the use of this technique, quantum dot lasers grown directly on Si exhibit relatively low threshold current (J th=900 A/cm2) and very high temperature stability (T 0=278 K). Integrated quantum dot lasers and quantum-well electroabsorption modulators on Si have been achieved, with a coupling coefficient of more than 20% and a modulation depth of ~100% at a reverse bias of 5 V. The monolithic integration of quantum dot lasers with both amorphous and crystalline Si waveguides, fabricated using plasma-enhanced chemical-vapor deposition and membrane transfer, respectively, has also been demonstrated.

Chip-scale integration of optoelectronic devices such as lasers, waveguides, and modulators on silicon is prevailing as a promising approach to realize future ultrahigh speed optical interconnects. We review recent progress of the direct epitaxy and fabrication of quantum dot (QD) lasers and integrated guided-wave devices on silicon. This approach involves the development of molecular beam epitaxial growth of self-organized QD lasers directly on silicon substrates and their monolithic integration with amorphous silicon waveguides and quantum well electroabsorption modulators. Additionally, we report a preliminary study of long-wavelength (>1.3 µm) Q D lasers grown on silicon and integrated crystalline silicon waveguides using membrane transfer technology.

In this paper, a comprehensive analytical study on the linearity of both CE and CB SiGe HBTs is presented for the first time. The linearity comparison between CE and CB SiGe HBTs was also made and experimentally verified at 1.9 GHz

The characteristic bias dependence of SiGe HBT linearity and power gain under both common-emitter and common-base configurations is experimentally studied and verified with simulations. Higher power-gain and better linearity can be obtained from the CB than CE configuration.

Crystalline semiconductor nanomembranes (NMs), which are transferable, stackable, bondable and manufacturable, offer unprecedented opportunities for unique and novel device applications. We report here nanophotonic devices based on stacked semiconductor NMs on Si, glass and flexible PET substrates. Photonic crystal Fano resonance-based surface-normal optical filters and broadband reflectors have been demonstrated with unique angle and polarization properties. Flexible photodetectors and solar cells have also been developed based on the NM stacking processes. Such NM stacking process can lead to a paradigm shift on silicon photonic integration and inorganic flexible photonics.

Publisher Summary This chapter discusses the fast flexible electronics made from nanomembranes derived from high-quality wafers. The organic polymer-based flexible electronics exhibit extraordinary flexibility, bendability, and stretchability. The ideal materials for high-speed applications are high-mobility (also high saturation velocity if used for high-power devices) materials. This also holds for high-speed flexible electronics (fast flexible electronics). The material list for potential fast flexible electronics includes carbon nanotubes, grapheme, and a number of single crystal inorganic semiconductors. Carbon nanotubes have very high intrinsic carrier mobility. However, they have been difficult to use owing to the difficult manipulation of individual tubes, the difficulty of realizing low contact resistance, some alignment issues and the difficulty in separating metallic and semiconductor tubes. Single-crystal inorganic semiconductors recently emerged as a very promising semiconductor material for fast flexible electronics. Obtaining these materials in very thin forms has been the key to their practical application.

Flexible photodetectors were demonstrated experimentally on large-area crystalline silicon nanomembranes (3 mmx3 mm), based on wet transfer and metal-frame supported transfer processes. Very low dark current (a few nA) and linear photoresponses were demonstrated for both Si MSM and InP PIN photodiodes on flexible PET substrates.

Linearity characteristics in terms of two-tone third order intermodulation distortion (IMD3) for common- emitter (CE) SiGe heterojunction bipolar transistors (HBT) are investigated at high frequency (6 GHz) with impedance matched for maximum output power. An approach to enhancing the linearity of SiGe HBTs at their high input power levels through the use of current bias instead of voltage bias is presented for the first time. Both measurements and simulations show that SiGe HBT linearity under high input power level (severe gain compression) can be improved. The reasons responsible for the linearity enhancement are discussed. distortion of SiGe HBTs, it is feasible to enhance the linearity properties of the devices by appropriately choosing the bias topology. Since high input power operation is desired to extract the highest power performance of SiGe HBTs, whether the linearity of the devices at high input power levels can be improved using different bias topologies is of significant importance. In this paper, the linearity characteristics of SiGe HBTs in terms of two-tone third order intermodulation distortion (IMD3) are studied under impedance matched condition (for power amplification) at high input power levels (up to 10dBm input power for devices of small size (emitter area: 60 μm 2 )). The linearity characteristics of the SiGe HBTs under current bias are investigated and compared with that under voltage bias conditions. Both measurements and simulations are used to verify the results. The reasons for the linearity differences using the two bias schemes are discussed.

Compound-semiconductor-based photonic devices, including lasers and modulators, directly grown and on-chip integrated on Si substrates provide a promising approach for the realization of optical interconnects with CMOS compatibility. Utilizing quantum dots as efficient dislocation filters near the GaAs-Si interface, for the first time, we demonstrated high-performance InGaAs/GaAs quantum dot (QD) lasers on silicon with a relatively low threshold current density (J, h = 900 A/cm 2 ), large small-signal modulation bandwidth of 5.5 GHz, and a high characteristic temperature (T 0 = 278 K). The integrated InGaAs QD lasers with quantum well (QW) electroabsorption modulators, achieved through molecular beam epitaxy (MBE) growth and regrowth, exhibit a coupling coefficient greater than 20% and a modulation depth ∼100% at 5 V reverse bias. We achieved the monolithic integration of amorphous and crystalline silicon waveguides with quantum dot lasers by using plasma-enhanced-chemical-vapor deposition (PECVD) and membrane transfer, respectively. Finally, preliminary results on the integration of QD lasers with Si CMOS transistors are presented.

Large-signal power performance of SiGe power HBTs are compared between common-emitter (CE) and common-base (CB) configurations with different layout structures and different unit subcells. Experiment results show that at high frequency (6 GHz), CB SiGe power HBTs have both higher small-signal and large-signal power gain values than the CE configuration. With optimization of layout and unit subcells, the power performance of both CE and CB SiGe power HBTs is significantly improved. The CB SiGe HBTs maintain the superior power gain characteristics over the CE SiGe HBTs in high frequency range, while CE SiGe HBTs become superior to CB SiGe HBTs in the low frequency range. The reasons for the device performance improvement and rules of optimizing power cell layout are discussed.

The influence of ballasting resistor implementations on the RF performance (both small-signal and large-signal) and on the linearity of common-base (CB) SiGe power HBTs is experimentally investigated. It is demonstrated that higher RF performance and better linearity can be achieved from CB SiGe HBTs by using emitter ballasting scheme than using base ballasting scheme.

This paper presents the RF (6 GHz) power performance characteristics of SiGe power HBTs at cryogenic (77K) and high operation temperature (chuck temperature 120deg C, junction temperature up to 160degC). It shows that, without specific device optimizations for cryogenic operation, the power SiGe HBTs exhibit excellent large-signal characteristics at 77K. Comparing with room-temperature operation, similar power gain, output power and PAE were obtained when the devices were operated at the cryogenic temperature. The SiGe power HBTs also operate well at high junction temperature with reasonable power gain and output power degradations. The modeling of the SiGe power HBTs under high operation temperature indicates significant increase of base resistance (RB) and emitter resistance (RE) that account for the degradation of power performance of these devices.

Minimum noise figure (NFmin) of SiGe HBTs under common-base (CB) configuration is analyzed through noise modeling, calculation and measurements and compared with that under CE operation configuration. Results show that the two configurations have similar NF min at low frequencies. At high frequencies, the CB configuration has higher NFmin than the CE configuration, while higher gain is exhibited by the CB configuration than the CE configuration. Tradeoff between NFmin and power gain ought to be considered for circuits design in employing different configurations

Linearity characteristics between common-emitter (CE) and common-base (CB) SiGe HBTs are compared at different frequencies, under different bias conditions and at different input/output matching conditions in this paper. It is shown that, without impedance matching at input/output of the devices, the CB configuration exhibits better linearity than the CE configuration under the same input power level and the difference of IMD3 between the two configurations decreases with the increase of operation frequency. However, when both input and output of the devices are impedance-matched for maximum output power Pout , the CE configuration has better linearity than the CB configuration. Furthermore, without varying the input/output matching, the linearity of the two configurations varies with bias in different ways that the linearity of the CE configuration degrades and that of the CB configuration improves as the bias is increased. Under certain impedance and bias conditions, the CB configuration can provide better linearity, besides higher power gain, than the CE configuration

The mechanical stress induced by shallow trench isolation (STI) signifilcantly affects the device behavior in the advanced CMOS technology. This paper presents an STI-dependent gate-induced drain leakage (GIDL) model and investigates the physical mechanisms in this phenomenon. Our simulation indicates that STI-induced compressive stress causes energy band gap narrowing. As a consequence, the effective tunneling barrier height becomes lower and intrinsic carrier concentration increases. These two factors enhance band-to-band tunneling (BBT) and trap-assisted tunneling (TAT), respectively. And an asymmetric layout is proposed to reduce the GIDL current.

The unique device structures of SiGe HBTs, in comparison to Si bipolar homojunction transistors (BJTs), allow us to reconsider the value of common-base (CB) configuration for high-frequency amplifications. In this paper, an omni-directional comparison between common-emitter (CE) and common-base SiGe power HBTs is made. By comparing the power gain, power handling, linearity, noise and stability characteristics between these two configurations, significant advantages for circuit design can be obtained by using the proper configuration of SiGe HBTs for certain amplifier applications

Linearity characteristics and dynamic loadlines of common-emitter (CE) and common-base (CB) configuration SiGe HBTs are analyzed and compared at 6GHz under different bias conditions. It is shown that the CB configuration can have both higher power gain and better linearity than the CE configuration under certain bias conditions. Dynamic loadlines of CE and CB configurations are compared and correlated with the linearity of SiGe HBTs under different DC bias conditions. Unlike the CE configuration, of which the linearity characteristic is almost independent of DC bias, it is shown from dynamic loadlines that the linearity of CB SiGe HBTs can be significantly improved by varying the bias conditions

This Letter presents the realization and characterizations of the flexible radio-frequency (RF)/microwave switches on plastic substrates employing single-crystal germanium (Ge) nanomembranes. The fabricated flexible Ge single-pole, single-throw (SPST) switches display high frequency responses (e.g., insertion loss of 10 dB at up to ∼13 GHz). RF performance tradeoff exists for the flexible Ge switches and the major affecting parameters are determined. The flexible Ge SPST switch shows better RF property to that of the flexible Si SPST switch. Underlying mechanism is investigated by theoretical analysis and modeling of switches with different structures.

In this letter, comprehensive experimental characterization and modeling of the bending strain effect on flexible microwave diodes and switches are conducted. The flexible microwave devices/circuits indicate different performance dependence with bending strains under different bias conditions. It is observed that individual diodes and switch circuits have the same dominant factors (series resistance and inductance) for radio frequency properties under bending conditions. More importantly, variations of the dominant factors are almost only dependent on the strains and regardless of diode areas or connection topology. The study provides guidelines for designing and using high-speed diodes/switches for flexible monolithic microwave integrated circuits.

This letter presents radio frequency (RF) characterization of flexible microwave switches using single-crystal silicon nanomembranes (SiNMs) on plastic substrate under various uniaxial mechanical tensile bending strains. The flexible switches shows significant/negligible performance enhancement on strains under on/off states from dc to 10 GHz. Furthermore, an RF/microwave strain equivalent circuit model is developed and reveals the most influential factors, and un-proportional device parameters change with bending strains. The study demonstrates that flexible microwave single-crystal SiNM switches, as a simple circuit example towards the goal of flexible monolithic microwave integrated circuits, can be properly operated and modeled under mechanical bending conditions.

Inexpensive polycrystalline Si (poly-Si) with large grain size is highly desirable for flexible electronics applications. However, it is very challenging to directly deposit high-quality poly-Si on plastic substrates due to processing constrictions, such as temperature tolerance and residual stress. In this paper, we present our study on poly-Si membranes that are stress free and most importantly, are transferrable to any substrate including a low-temperature polyethylene terephthalate (PET) substrate. We formed poly-Si-on-insulator by first depositing small-grain size poly-Si on an oxidized Si wafer. We then performed high-temperature annealing for recrystallization to obtain larger grain size. After selective doping on the poly-Si-on-insulator, buried oxide was etched away. By properly patterning the poly-Si layer, residual stress in the released poly-Si membranes was completely relaxed. The flat membrane topology allows the membranes to be print transferred to any substrates. High-performance TFTs were demonstrated on the transferred poly-Si membranes on a PET substrate.

This letter presents radio frequency (rf) characterization of flexible microwave single-crystalline silicon nanomembrane (SiNM) p-intrinsic-n (PIN) diodes on plastic substrate under various uniaxial mechanical tensile bending strains. The flexible single-crystalline SiNM PIN diode shows significant/negligible performance enhancement on strains under forward/reverse operation modes from dc to 20 GHz. An rf strain equivalent circuit model is developed to analyze the underlying mechanism and reveals unproportional device parameters change with bending strains (∼0.4% tensile strain induces ∼10% change for diode internal and parasitic inductance/resistance). The study provides guidelines of properly designing and using single-crystalline SiNMs diodes for flexible monolithic microwave integrated circuits.

Multigigahertz flexible electronics are attractive and have broad applications. A gate-after-source/drain fabrication process using preselectively doped single-crystal silicon nanomembranes (SiNM) is an effective approach to realizing high device speed. However, further downscaling this approach has become difficult in lithography alignment. In this full paper, a local alignment scheme in combination with more accurate SiNM transfer measures for minimizing alignment errors is reported. By realizing 1 μm channel alignment for the SiNMs on a soft plastic substrate, thin-film transistors with a record speed of 12 GHz maximum oscillation frequency are demonstrated. These results indicate the great potential of properly processed SiNMs for high-performance flexible electronics.

The performance of a SiGe heterojunction bipolar transistor (HBT) millimetre-wave power amplifier (PA) operating at cryogenic temperature was reported and analysed for the first time. A 24 GHz two-stage medium PA employing common-emitter and common-base SiGe power HBTs in the first and the second stage, respectively, showed a significant power gain increase at 77 K in comparison with that measured at room temperature. Detailed analyses indicate that cryogenic operation of SiGe HBT-based PAs mainly affects (improves) the performance of the SiGe HBTs in the circuits due to transconductance enhancement through magnified, favourable changes of SiGe bandgap due to cooling (ΔEg/kT) and minimized thermal effects, with little influence on the passive components of the circuits.

Common-emitter (CE) configuration of bipolar junction transistors has been used in virtually all amplifications since the invention of transistor, whereas common-base (CB) configuration has been rarely used due to its inferior performance in comparison to CE. For heterojunction bipolar transistors (HBTs) this conviction needs to be changed. We compared the radio-frequency (rf) power handling capability of the HBT between CE and CB configurations and analyzed their amplification mechanisms. It is found that CB HBT significantly outperforms CE HBT under proper bias conditions, revealing the significant superiority of CB to CE configuration of HBTs for rf power amplification.

Large-area (3x3 mm(2)) flexible photodetectors were realized, based on crystalline InP semiconductor nanomembranes transferred to flexible polyethylene terephthalate substrates. Very low dark curre ...

This letter reports the realization of bendable inductors and capacitors integrated on a polyethylene terephthalate substrate that can operate at high microwave frequencies. A low-temperature fabrication process compatible with flexible thin-film transistors (TFTs) was developed. By employing bendable dielectric materials, spiral inductors and metal-insulator-metal capacitors with high quality factors and high resonance frequencies were demonstrated. The effects of mechanical bending on the performance of inductors and capacitors were also measured and analyzed. These demonstrations combined with previously demonstrated microwave TFTs will lead to flexible radio-frequency and microwave systems in the future.

This paper reports the realization of flexible RF/microwave PIN diodes and switches using transferrable single-crystal Si nanomembranes (SiNM) that are monolithically integrated on low-cost, flexible plastic substrates. High frequency response is obtained through the realization of low parasitic resistance achieved with heavy ion implantation before nanomembrane release and transfer. The flexible lateral SiNM PIN diodes exhibit typical rectifying characteristics with insertion loss and isolation better than 0.9 dB and 19.6 dB, respectively, from DC to 5 GHz, as well as power handling up to 22.5 dBm without gain compression. A single-pole single-throw (SPST) flexible RF switch employing shunt-series PIN diode configuration has achieved insertion loss and isolation better than 0.6 dB and 22.9 dB, respectively, from DC to 5 GHz. Furthermore, the SPST microwave switch shows performance improvement and robustness under mechanical deformation conditions. The study demonstrates the considerable potential of using properly processed transferrable SiNM for microwave passive components. Future investigations on transferrable SiNMs will lead to eventual realization of monolithic microwave integrated systems on low-cost flexible substrates.

Crystalline semiconductor nanomembranes (NMs), which are transferable, stackable, bondable and manufacturable, offer unprecedented opportunities for unique and novel device applications. We report and review here nanophotonic devices based on stacked semiconductor NMs that were built on Si, glass and flexible PET substrates. Photonic-crystal Fano resonance based surface-normal optical filters and broadband reflectors have been demonstrated with unique angle and polarization properties. Such a low temperature NM stacking process can lead to a paradigm shift on silicon photonic integration and inorganic flexible photonics.

This letter presents realization of bendable rf switches operating at microwave frequencies formed with single-crystal Si nanomembranes (SiNMs) on a plastic substrate. Selectively doped 200-nm-thick SiNM is lifted off from silicon-on-insulator and transferred to a polymer substrate to form lateral P-intrinsic-N (PIN) diodes with minimized parasitic resistances. A single-pole single-throw switch, consisting of two PIN diodes connected in a shunt-series configuration, demonstrated very low insertion loss and high isolation from dc up to 20 GHz. The level of performance indicates a promise of properly processed single-crystal semiconductor nanomembranes for high-frequency applications in a number of consumer and military systems.

Off-axis silicon wafers promise monolithic integration of III-V optoelectronics with silicon microelectronics. However, it is unclear how miniaturization affects electronic device performance on off-axis substrates. We present the fabrication and characterization of metal-oxide-semiconductor field-effect transistors (MOSFETs) with different gate lengths on regular Si(100) and 4° off-axis wafers. The field-effect electron mobility in the off-axis devices is lower than in their (100)-wafer counterparts with equivalent gate length. Monte Carlo simulations have reproduced the experimental data and demonstrated that the mobility degradation in off-axis devices stems from enhanced electron scattering from the Si/SiO2 surface roughness. Short-channel MOSFETs on (100) and off-axis substrates perform comparably.

By generating high resolution two dimensional temperature images of electronic devices and linking heat dissipation to electrical current, the authors demonstrate that thermoreflectance measurements employing a charge-coupled device can provide a useful and nondestructive method for profiling current density in electronic devices. Here they apply this method to high power SiGe heterojunction bipolar transistors (HBTs) integrated in a commercial SiGe bipolar complementary metal-oxide-semiconductor platform, measuring the current carried by each subcell and quantifying current collapse under high-bias operation. They show that current hogging for a HBT with two emitter subcells can lead to one subcell carrying 81% of the total current.