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The effects of plasma irradiation in arsenic plasma doping are studied by applying overhang masks (OHMs) to fin structures. The spread resistance at the fin sidewall is ∼5 times higher at the shadowed part beneath the OHM than at the part exposed to ion flux. A cross-sectional transmission electron microscope (TEM) image shows an amorphous layer of ∼2 nm thickness at the sidewall shaded by the OHM increases to ∼5 nm as it separates from the edge of the OHM shadow. Near the fin bottom, the thickness increases rapidly, which may be caused by the decrease in the slope of the fin sidewall. These features are understandable in the context of the ion-assisted doping mechanism.

New doping processes which can alternate the ion implantation to achieve the ultra shallow junction are reviewed. Mainly two ways have been proposed. One uses plasma and the other uses vapor phase reaction. 0.17μm Surface Channel (SC) - PMOSFET's have been successfully fabricated by especially plasma doping method.

Key parameters for achieving n-type conformal doping desirable for source/drain extension regions of Si n-channel fin field effect transistors (FinFETs) have been determined for self-regulatory plasma doping using an AsH3 plasma diluted with He. Two-dimensional scanning spreading resistance microscopy revealed that this technique is advantageous for conformal doping of fin structures. An excellent resistivity conformality was obtained with the ratio of the resistivity of fin sidewall to that of the fin top surface being 0.85. A high total gas flow rate and a high AsH3 concentration were found to be important conditions for realizing conformal doping. The results revealed that a short gas residence time and high molar concentrations of AsH3 and He in the process chamber are essential physical parameters for realizing large amounts of dopant species with finite decomposition times. When these conditions are realized, a sufficiently large amount of As is supplied to both the top surface and the sidewall so t...

Reactive ion etching (RIE)-lag, i.e., the dependence of contact etched depth D on contact diameter φ, for deep quarter micron contact hole etching has been studied down to 0.1 µm contact. The nonlinearity between φ and D was found to be successfully converted into a linear relationship with reciprocal plots of φ and modified contact etched depth (D+h), taking into account the resist thickness h. In addition, by introducing the dependence on etching time t as the intercept in the relationship, the simple experimental equation was proposed in a new form to describe RIE-lag. This permits the prediction of etching rates of smaller contacts in the future and will be useful to investigate the etching mechanism.

Fluorocarbon CF x (x=1, 2) radicals in an inductively coupled plasma (ICP) have been measured using a spatially and temporally resolved laser-induced fluorescence (LIF) technique. Hollow profiles in the radial and axial distributions for the radicals in C4F8 ICPs, in contrast to uniform radial profiles near the substrate, suggest a destructive character within the ICP bulk and a small surface loss probability on the chamber wall. Temporal change of the CF2 radical distribution in the afterglow ICP was found to be dominated by the slow diffusion and wall-reflection processes.

This paper presents very thin InGaAsP/InP layers grown by the LPE-sliding growth technique and the characterization of the fabricated multiquantum well (MQW) layers. In the LPE growth mechanism of the very thin layer, the transient region having a thickness of 60 to 75 A is formed at the onset of the growth under nonequilibrium conditions of the solid-liquid interface, while a very thin layer is grown under diffusion-limited conditions. For MQW layers, the degeneration split between the heavy- and light-hole levels has been recognized from the photoluminescence measurements, and ±1st and ±2nd order satellite peaks of the superlattice have been observed in the rocking curves of the double X-ray diffraction. Furthermore, it has been recognized that the lattice constant of the very thin layers in the LPE-grown InGaAsP/InP MQW layers was shifted to that of the InP layers by the relaxation of the strain at the heterointerfaces.

The spectral linewidth and resonant frequency characteristics of 1.3- mu m InGaAsP/InP multi-quantum-well lasers grown by liquid-phase epitaxy were investigated and compared to those of the conventional double heterostructure (DH) lasers. A decrease in spectral linewidth and an increase in resonant frequency f/sub r/ with decreasing well thickness were observed. Moreover, the linewidth enhancement factor alpha was reduced to approximately 2 for well thicknesses of less than approximately 200 AA, while that of the DH laser was approximately 6. An f/sub r/ of 9 GHz, which is twice as large as that of conventional DH lasers, was achieved at an optical power of 5.3 mW/facet. >

The high‐quality ZnSe‐ZnS strained‐layer superlattices (SLSs), as well as the ZnS layers, were successfully grown for the first time on Si substrates. Photoluminescence (PL) spectra of ZnS layers grown on Si showed an intense excitonic‐emission line. In transmission electron microscopy analyses, no misfit dislocations and no moire fringes were observed on the ZnS layer with a thickness of less than about 500 A. We have also characterized ZnSe‐ZnS SLSs grown on Si substrates. By the PL measurements, an intense excitonic‐emission line, and no emissions due to deep levels, were observed. As the ZnSe well‐layer thickness decreased, the peak of the line largely shifted towards the higher‐energy side. This behavior may be related to the quantum size effect. In the temperature dependence of PL intensity, there appeared the thermal quenching process, which may be related to the thermal release of excitons in quantum wells. As the thickness of the ZnSe well‐layer decreased, the activation energy abruptly increased...

An InGaAsP( λ g = 1.2 μ m)/InP DHBT for use wavelength (1.3—1.55 μm) OEICs has been successfully fabricated, on a semi-insulating Fe-doped InP substrate, by a low pressure MOVPE method. Current-voltage characteristics of the emitter-base and base-collector junctions exhibit ideality factors of 1.81 and 1.34, respectively, and almost the same built-in voltages of 0.9 V, indicating that the p-n junctions are formed at the heterointerfaces of p-InGaAsP and n-InP, which is consistent with a SIMS analysis of the impurity depth profile. The common emitter characteristics of a typical DHBT show no offset voltage, small Farly effect, and a higher breakdown voltage of more than 10 V. The current gain ( h FE ) is about 160 at a collector current ( I c ) of 10 mA. The h FE has a small dependence on I c in the range from 1 μA to 10 mA ( h FE ∼ I 0.25 c ). The dependence of the cutoff frequency ( f T ) on the I c shows that the best f T is 3.6 GHz at I c = 20 mA.

The heterointerface abruptness of the InGaAs/InP system grown by liquid phase epitaxy (LPE) has been evaluated by secondary ion mass spectrometry (SIMS), Raman and C − V analyses. From these analyses, it is found that the interface abruptness decreases with lowering the growth temperature, due to the formation of a metastable InGaAsP intermediate layer in the InGaAs/InP heterointerface.

This paper reports the fabrication and lasing characteristics of 1.3‐μm InGaAsP multiquantum‐well (MQW) buried heterostructure (BH) lasers grown by liquid‐phase epitaxy (LPE) technique. The MQW active region consists of five InGaAsP well layers (λg=1.3‐μm, Lz∼200 A and InGaAsP barrier layers (λg=1.1 μm, d∼400–600 A). These lasers have threshold currents of 15–20 mA at 25 °C, external quantum efficiencies of 50% at 25 °C, and T0 values of 130–145 °K in the temperature range of less than 300 °K. The beam divergences perpendicular and parallel to the junction plane were in the narrow range of 10–13°. Furthermore, the polarization‐dependent gain‐current relationship between the TE and TM mode of InGaAsP MQW lasers has been investigated in detail for the first time.

The interfacial reaction between thermally oxidized In1−xGaxAsyP1−y and an In1−xGaxAsyP1−y epilayer was studied using Raman and x-ray photoelectron spectroscopy (XPS) analyses. In Raman spectra, it was found that the appearance of the phonon modes, i.e., the first-order longitudinal (LO) and transverse-optical (TO) modes for crystalline arsenic, was due to the In1−xGaxAsyP1−y -oxide interfacial reaction. The XPS analyses showed that this reaction corresponded to the GaAs-oxide interfacial reaction, i.e., As2O3+2GaAsGa2O3+4As. Furthermore, the reaction depends on the composition y of In1−xGaxAsyP1−y, which may be due to the enhancement in the initial transient reaction by thermal damage of In1−xGaxAsyP1−y occurring at the interface. Journal of Applied Physics is copyrighted by The American Institute of Physics.

This paper describes a Raman study of (Al x Ga 1− x ) 0.5 In 0.5 P quaternary alloys lattice-matched to GaAs over a whole range of composition. First, it has been confirmed that the Raman spectrum of the quaternary alloy has three-modes corresponding to the three binary compositions: AlP-, GaP-, and InP-like phonon mode. Second, the phonon spectra depend on the growth condition due to atomic arrangement differences in the sub-lattice. Finally, resonant Raman scattering has been observed for the first time in Al rich quaternary alloys. It is thought that resonant behavior may occur at an incident photon energy level in the vicinity of the E 0 energy gap.

The Zn auto-doping phenomenon of DH structures grown by LPE was evaluated, using photoluminescence (PL) and SIMS analyses. From these analyses, it was found that Zn contamination of an undoped epitaxial film is rather large when a highly Zn-doped melt is adjacent to an undoped melt, and this amount is 5% of the total Zn doping level. But, if the melts are separated, the contamination can be much decreased to only 0.5% and as a result the undoped InGaAsP epi-layer contains much less Zn introduced from the heavily Zn doped InP layer.

Multi‐quantum‐well (MQW) strip‐loaded waveguides, which are composed of liquid‐phase‐epitaxy‐grown InGaAsP/InP systems, have been characterized in detail. Several MQW waveguides with well depths (Lz) ranging from 100 to 240 A have been compared with bulk ones about the electric‐field‐induced absorption effect, considering the zero‐bias propagation loss and the optical confinement factor in the region in which absorption occurs. It has been confirmed that the MQW (Lz∼100 A) waveguides have an absorption change under the electric field more than five times larger than the bulk ones with the same zero‐bias propagation loss.

We have demonstrated a new cracking method, which uses a self-cracking system (SCS), for group V hydrides such as PH 3 and AsH 3 in the MOCVD growth of In 1− x Ga x As y P 1− y and ( Al x Ga 1− x ) y In 1− y P using triethylindium (TEI) as a source material. The SCS can be explained as follows; PH 3 and/or AsH 3 are introduced by passing through a line located near the RF-heated susceptor into the reactor tube, resulting in pre-cracking of the PH 3 and/or AsH 3 before they are mixed with TEI. By the use of this SCS, we have found that the In atom is introduced into the solid more effectively than with conventional methods. In particular, for the case of the MOCVD growth of In 1− x Ga x As y P 1− y , it was found that the low-pressure-SCS (LP-SCS) method is most suitable for the incorporation of both In and P. Details of the growth conditions, electrical and optical properties of epitaxial layers are also presented. This SCS is one of the most promising techniques for the MOCVD growth of compound semiconductors using TEI.

Low-loss ( α = 0.7 cm −1 ) short-wavelength optical waveguides using ZnSeZnS strained-layer superlattices (SLSs) were successfully fabricated on GaAs substrates by low-pressure metalorganic vapor phase epitaxy. These waveguides exhibited a large difference in the propagation loss between TE and TM polarizations under some conditions. It is supposed that the difference in the losses may be related to the birefringence of the SLS's. Therefore, we investigated the phase retardation between the TE and TM modes in the waveguide output. From these results, the numerical values for the birefringence were estimated to be 5.8 × 10 −3 for 80 periods of ZnSe(50 A)ZnS(50 A) and 4.25×10 −3 for 100 periods of ZnSe(25 A)ZnS(50 A).

We have been developing InGaAs/InP monolithic PIN/Amplifiers. This paper describes the consideration to use self-aligned FETs with a view to improving the operating speed. To this end, the device structure and the fabrication process have first been discussed for integrating the self-aligned JFETs and photodiodes. Next, photodiodes and FETs of this configuration have been fabricated and their characteristics evaluated. It was found that the dark current of the photodiode could be reduced to 2.7 nA at −3 V and that the cutoff frequency of the FET was improved to be 3.0 GHz. Finally, a monolithic PIN/Amplifier was fabricated. Presently, the frequency characteristics of fabricated PIN/Amplifiers are not so good. This is believed to be caused by the fact that the gate electrode of the FET is a Schottky electrode. If this problem is settled in the future, a PIN/Amplifier with a 3-dB bandwidth of about 700 MHz can be realized.

Strained-layer Superlattices (SLS) ZnSe-ZnS grown by low pressure Metalorganic Vapor Phase Epitaxy (MOVPE) on the GaAs substrates show almost no Raman frequency shifts of the ZnSe LO-phonon. On the contrary ZnS LO-phonon shifts to the low energy side due to the biaxial tensile strain in the ZnS layers. Near-resonant Raman scattering and photoluminescence measurements show the quantum-size effect in superlattices with different ZnSe (well) layer thicknesses.

High‐quality ZnSe layers have been successfully grown on ZnS layers with an intermediate ZnSe‐ZnS strained‐layer superlattice (SLS) by low‐pressure metalorganic vapor‐phase epitaxy. If we use the SLS buffer between the ZnSe and ZnS layer, the excitonic‐emission line in the photoluminescence spectra of the ZnSe epilayers due to the free exciton becomes stronger and emissions related to misfit dislocations weaker compared with those of the ZnSe layer grown directly on the ZnS layer. Reflective high‐energy electron diffraction measurements also showed that these (100) ZnSe layers grown on the SLS buffer were single crystals. With double‐crystal x‐ray diffraction, it is supposed that the misfit strain was completely relaxed by using the SLS buffer in only 0.6‐μm‐thick ZnSe layer grown on the ZnS layer. From these results, we have found that the ZnSe‐ZnS superlattice buffer is very useful for obtaining a good ZnSe/ZnS heterostructure.

Low‐loss short‐wavelength optical ridge waveguides using ZnSe‐ZnS strained‐layer superlattices (SLS’s) were successfully fabricated on GaAs substrates by low‐pressure metalorganic vapor phase epitaxy. A propagation loss α as low as 0.71 cm−1 was obtained for the SLS waveguide composed of 80 periods of ZnSe(50 A)‐ZnS(50 A) at the 0.633‐μm wavelength TE fundamental mode. Therefore, this waveguide may be suited for optoelectronic integrated circuits composed of II‐VI and III‐V compound semiconductor devices. Furthermore, these waveguides exhibited a large difference in the propagation loss between TE and TM polarizations which may be related to the birefringence for TE and TM polarizations due to the slight anisotropy of the refractive index in the ZnSe‐ZnS superlattice structure. This birefringence effect will be very useful for a polarizing optical device.

High quality ZnSe layers have been successfully grown by low pressure metalorganic vapor phase epitaxy (MOVPE) using methylalkyls, dimethylzinc, and dimethylselenide. Streaks and Kikuchi lines were observed by reflective high‐energy electron diffraction measurements. Also the sharp and strong excitonic emission line due to free exciton and no emissions related to deep levels or residual impurities were observed by photoluminescence measurements. These results show that the ZnSe layers are of good crystalline quality. Furthermore, good selective growth of the ZnSe films on structured substrates was easily achieved by using this low pressure MOVPE technique.

We present a new approach for calculation of the dependence of elastic strain on layer thickness concerning ZnSe films grown on GaAs and on ZnS. The basic concept involved in our model is that the interfacial misfit dislocations are generated only when the areal strain energy density exceeds an energy barrier. It is found that the elastic strain calculated by this model is quite in agreement with experimental results for the ZnSe/GaAs system with the energy barrier of 79 erg/cm2. To compare the theory with experiments, the difference of thermal expansion coefficient between the epitaxial layer and the substrate must be taken into consideration. Applications of the model to other systems are also discussed.

Good quality ZnSe‐ZnS strained‐layer superlattice (SLS) has been successfully fabricated for the first time by low pressure metalorganic vapor phase epitaxy (MOVPE) using methylalkyls (dimethylzinc, dimethylselenide, and dimethylsulfide). The satellite peak observed by x‐ray diffraction measurements and the periodic behavior of the atomic profiles by secondary ion mass spectrometry measurements confirm the formation of the SLS structure. From the photoluminescence measurements, the quantum size effect has been evidenced by the relationship between the ZnSe well‐layer thickness and the peak energy shift of the light emission. Our results show that low pressure MOVPE using VI group alkyls can be quite useful for the growth of ZnSe‐ZnS SLS.

Thermally deformed surface corrugations on both an InP substrate and an InGaAsP layer have been analyzed by means of x-ray photoelectron spectroscopy and laser Raman spectroscopy. From the spectra of the deformed surface corrugations on an InP substrate on which a GaAs wafer was placed during its heat treatment, it has been found that material formed in the grooves is an InGaAsP alloy single crystal. Applied Physics Letters is copyrighted by The American Institute of Physics.

A half inch size CCD area imaging device having the structure of the Photoconductive-Layer-On-Solid -Scanner(PLOSS) has been designed and fabricated for investigating the capability of applying the very small size image sensor to the compact-video-camera. A buried channel CCD is used as a scanner. A narrow and a short channel effects on the CCD potential well are also evaluated. As a sensor, ZnSe-ZnCdTe photoconductor is employed and vacuum-deposited on the CCD scanner to use the whole area on a Si chip as a photosensitive area. The device is designed for minimum size effect. The experimental device has 375(H) × 482(V) picture elements in the imaging area of 6.4(H) mm × 4.8(V) mm. The maximum handling charge of the CCD register is 1.7 × 105electrons/packet. The saturation signal current is 160 nA. The sensitivity of the device with the IR-cut filter is 0.018 µA/1ux. The SN ratio is above 60 dB(FPN). The blooming phenomenon is suppressed up to 150 times as intense as the saturation exposure within the 10 % smearing signal.

Dynamic spectral linewidths in InGaAsP multiquantum-well buried-heterostructure (BH) lasers grown by liquid-phase epitaxy (LPE) have been investigates. The results showed that the linewidths in the MQW lasers were smaller than in conventional DFB-BH lasers and that they decreased as the well width became smaller.

We report a Raman study of the phonon mode of (AlxGa1−x)0.51In0.49P quaternary alloys lattice matched to GaAs over the whole range of compositions. From the composition dependence of spectra it has been confirmed that the three‐mode behavior of the alloy corresponding to the three binary compositions: AlP‐, GaP‐, and InP‐like phonon modes may occur.

We have measured deep levels near the InGaAs/InP heterointerface by DLTS and C-V method. Three deep levels, E1, E2 and E3, have been found near the heterointerface, whose activation energies are 0.17 eV, 0.37 eV and 0.54 eV, respectively. The concentrations of E2 and E3 rapidly decrease when approaching the heterointerface from the InP, indicating that the two levels are located only in the InP substrate. The E1 level, on the other hand, can be found only near the heterointerface. The density of the E1 level is well correlated with the interface charge density which is determined by the C-V analysis. Both of the densities are dependent on the degree of the lattice mismatch between the InGaAs epitaxial layer and the InP substrate.

A new CCD imager, having ZnSe-ZnCdTe heterojunction photoconductor as a photosensor which is vacuum-deposited on the CCD scanner, has been fabricated. The device has 404 (H) × 506 (V) scanning elements, each element measures 24 µm(H) by 14 µm(V), and the imaging area is 9.0 mm(H) × 6.7 mm(V) in size which is applicable to 2/3 inch camera format. The CCD scanner is fabricated with denuded zone which defines the defect-free device. A glass-reflow process is introduced to obtain the high breakdown of the heterojunction diode. The experimental result are as follows,; The sensitivity is 0. 16 µA/lx (3200 K). The horizontal and the vertical resolution are 280 and 450 TV lines, respectively. Dark current is 2 nA/cm2 for the photosensor (27°C). The signal to noise ratio is above 60 dB. The smearing suppression is effective for reducing the blooming phenomenon under the intense light illumination. The successful blooming suppression is achieved by this PLOSS structure device with metal screen grid. The high light exposure is allowable up to 1000 times as intense as the saturation exposure.

We have demonstrated the MOCVD growth of InGaAs on an InP substrate under atmospheric pressure by cracking AsH3. The self-cracking system has been employed; AsH3 is introduced by passing near the rf-heated susceptor into the reactor tube, resulting in AsH3 cracking prior to its mixing with triethylindium and triethylgallium source materuals. The typical carrier concentration and Hall mobility obtained are 4.7×1016 cm-3 and 3,050 cm2/Vsec at room temperature, respectively. The half width of the photoluminescence spectrum is as narrow as 19 meV at 77 K. These results are comparable to those of liquid phase epitaxy grown InGaAs.

InGaAsP/InP multiquantum-well (MQW) structures have been successfully grown by low-pressure MOCVD. The abruptness of the As atom profile was measured to be 20 A by SIMS analysis. Continuous operation of InGaAsP/InP lasers using MQW structure has been achieved at 80 K.

Deep levels in undoped n-type InP epitaxial layers grown by MOCVD on Fe-doped InP substrates were investigated by DLTS and photo-excited DLTS. Two main electron traps, F1 and F2, were observed in the films. The concentration profile of F1 seems to be related to that of donors. The concentration of F2 increases as the substrate is approached, suggesting the out-diffusion of Fe from the Fe-doped substrate. The activation energy E n and the carrier capture cross section σn were found to be 0.48 eV and ∼6×10-19 cm2 respectively for F1; and 0.78 eV and 10-20∼10-21 cm2 respectively for F2 in the temperature range investigated. Another level was also detected in the Fe-doped substrate, and its E n and σ∞ were found to be 0.24 eV and 2×10-16 cm2, respectively. We speculate that either or both of these F1 and F2 traps are the origin of the substantial looping phenomenon in the drain I/V characteristics previously observed in InP MESFETs.

We have demonstrated the MOCVD growth of AlGaInP under low pressure using a self-cracking system (SCS) for the group V hydride (PH3). In InGaP growth, the incorporation efficiency of In atoms for the SCS method is higher than that for the conventional method. For AlInP growth, however, efficiency did not depend on growth methods or growth temperatures. The compositions of AlGaInP are independent of PH3 flow rates and growth temperatures. These results indicate that it is easy to control the alloy compositions of the AlGaInP/GaAs system using the SCS method, even though growth conditions fluctuate slightly.