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1.
The negative differential resistance (NDR) phenomena were observed in GaSb/AlSb/InAs/-GaSb/AlSb/InAs resonant interband tunnel structures. Electrons have resonantly achieved interband tunneling through the InAs/GaSb broken-gap quantum well. The InAs well width causes significant variations of the peak current density and NDR behaviors. The peak current density varies exponentially with the AlSb barrier thickness. The multiple NDR behavior was observed with appropriate InAs well and AlSb barrier thicknesses, e.g., 30 Å thick AlSb barrier and 240 Å wide InAs well. Only single negative resistance has, otherwise, been seen. The three-band model was used to interpret the effect of the InAs well and AlSb barrier on the current-voltage characteristics of GaSb/AlSb/InAs/GaSb/AlSb/InAs structures  相似文献   

2.
InAsP/InP multiquantum well structures were grown by solid source molecular beam epitaxy using either As2 or As4 over a substrate temperature range of 420–535°C. All quantum wells had similar arsenic compositions with a 2.2% standard deviation regardless of arsenic species or growth temperature. This temperature insensitivity of arsenic incorporation in InAsP is in sharp contrast to InGaAsP in which arsenic composition is very sensitive to both substrate temperature and gallium percentage in the compound. The insensitivity of arsenic incorporation in InAsP to substrate temperature may result from growth in a phosphorus rich condition with indium as the only available cation.  相似文献   

3.
The tunneling currents of GaSb/AlSb/GaSb/AlSb/InAs double-barrier interband tunneling (DBIT) structures were studied experimentally by varying the thickness of the well and the barrier layers systematically. The optimal thicknesses for the GaSb well and the AlSb barriers were found to be 6.5 and 1.0 nm, respectively, to obtain a high peak current density (19 kA/cm2), with a large peak-to-valley ratio of 4. The high peak current in the DBIT structure shows the strong effect of the resonant coherence of the wave function across the double barrier. For the case of a small GaSb well width (3 nm), a drastic reduction of the peak current was observed, an effect suggesting that the electron-wave function in the InAs couples primarily to the quantized light hole state in the GaSb well  相似文献   

4.
This study investigated the incorporation of arsenic dimers (As2), delivered from a “cracker” effusion cell. The HgCdTe epilayers were deposited under standard growth conditions. During deposition, arsenic was incorporated using both a standard arsenic effusion cell and a cracker cell. It was found that arsenic concentration rose dramatically as a function of cracker-zone temperature, particularly at temperatures above 600°C. This behavior was consistent with the temperature dependence of the effusion cell’s cracking efficiency, as determined by residual gas analysis. The temporal stability of the arsenic source was excellent. Arsenic concentrations of 2.8×1020 cm−3 were achieved at a cracker temperature of 800°C. The arsenic beam-equivalent pressure, estimated from an uncorrected, nude ion-gauge reading, was ∼8×10−7 mbar.  相似文献   

5.
A complementary heterojunction field effect transistor technology based on the InAs/AlSb/GaSb system is proposed. The structure is formed by the vertical integration of InAs n-channel and GaSb p-channel HFET devices. The superior transport properties of electrons in InAs and holes in GaSb and their band offsets to AlSb or AlSbAs yield devices with transconductances much greater than AlGaAs/GaAs n- and p-channel HFETs. It is shown that a complementary circuit fabricated from these devices could provide room-temperature performance up to six times greater than that predicted for AlGaAs/GaAs complementary circuits  相似文献   

6.
The p-type doping of Hg1−xCdxTe (MCT) has proven to be a significant challenge in present day MCT-based detector technology. One of the most promising acceptor candidates, arsenic, behaves as an amphoteric dopant which can be activated as an acceptor during Hg-rich, low temperature annealing of as-grown molecular beam epitaxy (MBE) samples. This study focuses on developing an understanding of the microscopic behavior of arsenic incorporation during MBE growth. In particular, the question of whether arsenic incorporates as individual As atoms, as As2 dimers, or as As4 tetramers is addressed for MBE growth with an As4 source. A quasithermodynamical model is employed to describe the MCT growth and As incorporation, with parameters fitted to an extensive database of samples grown at the Microphysics Laboratory. The best fits for growth temperatures between 175 and 185°C are obtained for arsenic incorporation as As4 or possibly as As4 clusters, with lower probabilities for As2 and individual As atoms. Based on these results, we investigate the relaxed atomic configurations of As4 and As2 in bulk HgTe by ab initio total energy calculations. The calculations are performed in the pseudopotential density-functional framework within the local density approximation, employing supercells with periodic boundary conditions. The lattice distortions due to As4 and As2 in bulk HgTe are predicted to be modest due to the small size of these arsenic clusters.  相似文献   

7.
The band structure of three-layer symmetric InAs/GaSb/InAs quantum wells confined between AlSb barriers is analyzed theoretically. It is shown that, depending on the thicknesses of the InAs and GaSb layers, a normal band structure, a gapless state with a Dirac cone at the center of the Brillouin zone, or inverted band structure (two-dimensional topological insulator) can be realized in this system. Measurements of the cyclotron resonance in structures with gapless band spectra carried out for different electron concentrations confirm the existence of massless Dirac fermions in InAs/GaSb/InAs quantum wells.  相似文献   

8.
We analyse the potentiality of InAs/GaSb/AlSb tunnel structures for creation of the population inversion and stimulated radiation both in the presence and in the absence of magnetic field.  相似文献   

9.
AlGaAsSb and GaAsSb alloys of different composition were grown by molecular-beam epitaxy (MBE) on GaSb, InAs, and GaAs substrates, using both conventional and cracker antimony effusion cells. The incorporation coefficients of dimer and tetramer antimony molecules, which totally describe the kinetic processes on the growth surface, were calculated. The differences in the incorporation of Sb2 and Sb4 molecules in MBE-grown GaAsSb alloys are shown. The effect of the MBE-growth parameters (substrate temperature and incident fluxes of group-V and group-III elements) on the composition of (Al,Ga)AsSb alloys and the incorporation coefficient of Sb was studied in detail. The incorporation coefficients of tetramer and dimer antimony molecules were found to vary over a wide range, depending on the substrate temperature and the ratio between the arrival rates of the group-III and the group-V elements.  相似文献   

10.
The purpose of this research is to demonstrate the necessity of computer controlled valved group V effusion cell sources in the growth of indium gallium antimonide/indium arsenide (InGaSb/InAs). These sources allow enhanced control of the group V flux. This flux control allows the reduction of unwanted cross contamination and complete control of the interface type. For simple structures, this control can be done manually, however, for complicated structures the control must be automated to allow for reproducibility and uniformity. The InGaSb/InAs strained layer superlattice (SLS) is an example of a complicated structure with hundreds of layers that requires interface type control. Arsenic incorporation with typical flux shuttering was found to be a problem in the growth of antimonide layers and limit interface type control. The antimony incorporation was not found to occur for the growth of arsenide layers. In addition, antimony exposure to critical interfaces did not appear to reduce the interface quality. This research demonstrates that the use of computer controlled valve sources is only required for the arsenic source when attempting to create InGaSb/InAs SLS structures.  相似文献   

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