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Coupling of metasurfaces to intersubband transitions (ISTs) in semiconductor quantum wells (QWs) has been extensively studied for various applications ranging from generating giant nonlinear optical response to designing tunable metasurfaces for applications such as ultrafast spatial optical modulators and voltage tunable filters. In this work, we experimentally demonstrate a fundamentally new approach of actively controlling the coupling of ISTs in QWs to a metasurface for voltage tuning its optical response. Unlike previous approaches, we use voltage-controlled quantum tunneling to control the carrier concentration in the QWs for turning on/off the ISTs. We design a multi-quantum well structure consisting of four undoped InGaAs wells with AlInAs barriers grown on top of a highly doped InGaAs layer that acts as an electron reservoir. The heterostructure is optimized such that the first IST in all the wells is at 11µm. A complementary gold metasurface with dipole resonances at 11µm is fabricated on top of the QW structure. We designed the heterostructure such that by applying a bias of 1V, the energy bands of all the QWs get aligned simultaneously, leading to the occupation of the ground state of all the QWs via quantum tunneling of the electrons from the electron reservoir. The ISTs which were turned off due to negligible electron density gets turned on at 1V, and this leads to coupling between the ISTs and the dipoles resonances of the metasurface. The voltage induced coupling leads to reflectance modulation which we confirmed experimentally by rapid scan double modulation FTIR measurements.

We demonstrate a fundamentally new approach of using voltage controlled quantum tunneling for modulating optical response of a metasurface coupled to intersubband transitions in semiconductor quantum wells.

In this letter, the first packaged THz solid-state amplifier operating at 0.85 THz is reported. The InP HEMT amplifier achieves a noise figure as low as 11.1 dB with an associated gain of 13.6 dB at 0.85 THz using high ${\bf f}_{\bf MAX}$ InP HEMT transistors in a 10-stage coplanar waveguide integrated circuit. Output power up to 0.93 mW is measured.

The ability to control the light-matter interaction with an external stimulus is a very active area of research since it creates exciting new opportunities for designing optoelectronic devices. Recently, plasmonic metasurfaces have proven to be suitable candidates for achieving a strong light-matter interaction with various types of optical transitions, including intersubband transitions (ISTs) in semiconductor quantum wells (QWs). For voltage modulation of the light-matter interaction, plasmonic metasurfaces coupled to ISTs offer unique advantages since the parameters determining the strength of the interaction can be independently engineered. In this work, we report a proof-of-concept demonstration of a new approach to voltage-tune the coupling between ISTs in QWs and a plasmonic metasurface. In contrast to previous approaches, the IST strength is here modified via control of the electron populations in QWs located in the near field of the metasurface. By turning on and off the ISTs in the semiconductor QWs, we observe a modulation of the optical response of the IST coupled metasurface due to modulation of the coupled light-matter states. Because of the electrostatic design, our device exhibits an extremely low leakage current of ∼6 pA at a maximum operating bias of +1 V and therefore very low power dissipation. Our approach provides a new direction for designing voltage-tunable metasurface-based optical modulators.

Heterostructure field-effect transistors (HFETs) composed of antimonide-based compound semiconductor (ABCS) materials have intrinsic performance advantages due to the attractive electron and hole transport properties, narrow bandgaps, low ohmic contact resistances, and unique band-lineup design flexibility within this material system. These advantages can be particularly exploited in applications where high-speed operation and low-power consumption are essential. In this paper, we report on recent advances in the design, material growth, device characteristics, oxidation stability, and MMIC performance of Sb-based HEMTs with an InAlSb upper barrier layer. The high electron mobility transistors (HEMTs) exhibit a transconductance of 1.3S/mm at VDS=0.2V and an fTLg product of 33GHz-μm for a 0.2μm gate length. The design, fabrication and improved performance of InAlSb/InGaSb p-channel HFETs are also presented. The HFETs exhibit a mobility of 1500cm2/V-sec, an fmax of 34GHz for a 0.2μm gate length, a threshold voltage of 90mV, and a subthreshold slope of 106mV/dec at VDS=-1.0V.

A wafer-level-packaging technology was used to integrate the 0.1 µm AlSb/InAs HEMT low-noise amplifiers with power amplifiers, switches and phase shifters to form a compact tri-stack transmit/receive module for light-weight and ultralow-power applications. The high manufacturability of AlSb/InAs HEMT receivers operating at 0.9 mW was demonstrated on a tri-stack wafer. This demonstration of manufacturable tri-stack transmit/receive modules is essential for phased-array applications requiring light weight and ultralow power.

The degradation mechanisms of 0.1 mum AlSb/InAs HEMTs subjected to elevated-temperature lifetesting at three temperatures in N2 atmosphere were investigated. Device degradation exhibits the increase of non-pinch-off drain current (IDS), the decrease of transconductance (gm) and the gate current (IG) increase. The IG increase was found to correlate with material degradation on the gate-recess and Al0.7Ga0.3Sb-mesa-floor surfaces. Higher oxygen content was detected on these surfaces, indicating that they were modified by oxidation, which resulted in the IG increase. Despite the degradation observed in 0.1 mum AlSb/InAs HEMTs, the three-temperature lifetesting shows that the activation energy (Ea) is approximately 1.5 eV and demonstrates a median time to failure (MTF)of 2times106 hours at Tjunction of 85degC. This reliability result is essential for successful insertion of AlSb/InAs HEMTs into systems with ultralow-power requirements. Moreover, ohmic-metal lateral diffusion of Pd and Au elements was observed. To avoid potential ohmic-metal-lateral-diffusion induced device failure, lifetesting temperatures were kept below 190degC in this investigation.

Three-temperature lifetesting was performed to evaluate the reliability performance of 0.1 μm AlSb/InAs HEMT low noise amplifiers (LNAs) for ultralow-power applications. For the first time, the reliability performance of 0.1 μm AISb/lnAs HEMT LNAs was demonstrated. The results show a median time to failure of approximately 2x106 hours at Tjunction of 85°C with activation energy of 1.5 eV. High-reliability performance is essential for successful insertion of 0.1 μm AISb/lnAs HEMT LNAs for military and space applications with ultralow-power requirements.

A 0.1 μm In02Al08Sb-InAs HEMT MMIC technology was developed for phased-array applications with ultralow-power and oxidation-free requirements. An In02Al08Sb layer was utilized to replace the upper AlSb layer in the conventional AlSb-InAs HEMT in order to mitigate the oxidation incurred by the AlSb layer. In this work, we have demonstrated excellent dc and rf performance on both devices and low-noise amplifiers (LNAs) using 0.1 μm In02Al08Sb-InAs HEMTs on 3-inch GaAs substrates. This accomplishment is crucial for phased-array applications with ultralow-power and oxidation-free requirements.

In this paper, we present a two-stage low-power/low-noise MMIC amplifier. At 10-GHz, the amplifier demonstrates high gain (~18-dB) and moderate noise figure (

In this paper, we report AlSb/InAs HEMT high frequency perfornance up to 260 GHz fT. The 0.1-μm gate length and 80-um total gate periphery devices exhibited a small-signal available gain of 10 dB at 100 GHz, and extrapolated fT and fmAx performance of 260 and 280 GHz, respectively at a drain voltage of 0.4 volts and drain current of 18 mA.

In this paper, we report record AlSb/InAs HEMT high frequency gain performance up to 275 GHz f/sub MAX/. The 0.1-/spl mu/m gate length and 80-/spl mu/m total gate periphery devices exhibited a small-signal available gain of 10 dB at 100 GHz, and extrapolated f/sub T/ and f/sub MAX/ performance of 220 and 275 GHz, respectively, at a drain voltage of 0.5 V and drain current of 27 mA. To the best of our knowledge, this is the highest reported f/sub MAX/ and high-frequency available gain reported for InAs-channel HEMTs. Furthermore, it is first AlSb/InAs HEMT result that has achieved f/sub MAX/ greater than f/sub T/, which clearly demonstrates that this approach is not intrinsically limited in regards to achieving high frequency and high-gain characteristics.

In addition to the significant impact that VCSELs have on design, performance and cost of fiber optic modules, there is a potential for high density integration for SONET in the form of 1.3 /spl mu/m InGaAsN VCSEL arrays.

Because of the large lattice mismatch between InAs and GaAs, the growth of the former on the (001) surface of the latter undergoes a well-known transition from a layer-by-layer mode to an island mode at an equivalent coverage of 1–2 monolayers (ML). We have observed a suppression of this transition when growth proceeds under a simultaneous thallium flux. The thallium is not significantly incorporated into the InAs layer; however, approximately I ML may remain at the interface. The effect of the thallium on the electronic properties of the InAs is investigated.