摘要:

p+‐InSb/&pgr;‐InAs1−xSbx/n+‐InSb heterojunction photodiodes operating at near room temperature in the 8–13 &mgr;m region of infrared (IR) spectrum are reported. A room‐temperature photovoltaic response of up to 13 &mgr;m has been observed at 300 K with anx≊0.85 sample. The voltage responsivity‐area product of 3×10−5V cm2/W has been obtained at 300 K for the &lgr;=10.6 &mgr;m optimized device. This was close to the theoretical limit set by the Auger mechanism, with a detectivity at room temperature of ≊1.5×108cm Hz1/2/W. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114323

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The homogeneity and luminescence properties of undoped bulk GaSb have been studied by the cathodoluminescence (CL) technique in the scanning electron microscope. CL images have revealed a nonuniform distribution of native defects in GaSb wafers prepared from as‐grown single crystals. Postgrowth annealing in vacuum, gallium, and antimony atmospheres has been performed to obtain more accurate information about the defect structure in this material. In general, on annealing, homogeneous distribution of impurities is observed throughout the wafers. CL spectra show that a luminescence band (centered at 756 meV) is enhanced by annealing in a gallium atmosphere, suggesting that Ga atoms play an important role in the formation of this acceptor center. The 756 meV peak has been attributed to a transition from conduction band to an acceptor center comprised of GaSbor a related complex. Interestingly, localized crystallization at the subgrain boundaries seems to occur by annealing in Ga atmosphere. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114324

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Boron‐doped homoepitaxial layers have been selectively grown on synthetic type Ib substrates of (100) cut. Ohmic contacts were formed by evaporating a Mo/Pt/Au sandwich and subsequent annealing at 950°C for h. Current–voltage characteristics of diode type could be taken in vacuum in the temperature range 360–900 °C. Green light emission due to electroluminescence was observed from the junction area showing a maximum at a wavelength of 534 nm corresponding to a photon energy of 2.32 eV. The normalized emission spectrum was measured over the temperature range 320–440 °C with the device in air and was found independent of temperature and boron concentration. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114325

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A nearly ideal Si(001) surface was prepared by a wet‐chemical method with a solution of HF:HCl=1:19 (pH<1). The surface was examined by scanning tunneling microscopy and was found to be covered by the uniform dihydride phase. Its successful preparation was the direct consequence of the following facts: The suppression of the (111) facet formation due to a low concentration of OH ions in the etchant solution and the stabilization of the surfaces structure due to the formation of the ordered steps. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114326

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Schottky barriers onn‐type GaN films grown by low‐pressure metalorganic chemical vapor deposition are characterized and derived. A thin Pt or a Pd layer is deposited by electron‐gun evaporation to form Schottky contacts in a vacuum below 1×10−6Torr. The Schottky barrier heights of Pt on then‐GaN film are determined to be 1.04 and 1.03 eV by current–voltage (C–V) and current density–temperature (J–T) measurements, respectively. Also based onC–VandJ–Tmeasurements, the measured barrier height of Pd onn‐GaN is 0.94 and 0.91 eV, respectively. Schottky characteristics of Pt and Pd observed in the experiment are compared with those of Au and Ti in previous reports. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114327

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A selective reactive ion etching process which etches InP and InGaAs, but not InAlAs, using a mixture of SiCl4/SiF4/HBr gases has been developed. Optical emission spectroscopy shows that the dominant emitting species in the plasma are HBr+, Br, and Br2, with a weaker emission from SiBr and SiHBr. We believe that the bromosilanes or chlorosilanes of the form (SiHxBry,SiHxCly) are responsible for the etching of these In‐containing compounds by the formation of indium bromosilanes and indium chlorosilanes. Using a flow rate ratio of SiCl4/HBr of 7/15 sccm, a pressure of 100 mTorr and with dc bias of 80 V, an etch rate of InGaAs and InAlAs as high as 100 nm/min at room temperature was achieved with good surface morphology. The addition of SiF4suppresses the etching of InAlAs and the selectivity obtained can be changed by varying the proportion of SiF4. At a flow rate ratio (SiCl4:SiF4:HBr) of 5/6/20 sccm, dc bias of ≤70 V and a pressure of 150 mTorr, the selectivity obtained is extraordinarily high (≳600:1) for this material system. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114328

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Amorphous 2CdO⋅GeO2thin films (optical band gap determined by a Tauc plot; 3.4 eV) prepared by rf sputtering were implanted with H+or Li+ions to a dose of 2×1016cm−2. Direct current conductivities in the specimens at 300 K were increased from 3×10−9S cm−1to ∼10 S cm−1after the implantation. The conductivities in these implanted specimens remained almost constant down to 77 K. No deleterious coloring was perceived after implantation. The Hall mobilities (conduction type;n) in the implanted specimens at ∼300 K were ∼5 cm2 V−1 s−1, which are larger by several orders of magnitude than those in existing amorphous semiconductors. Such a large mobility indicates that the electronic state near the bottom of the conduction band of this amorphous material is extended. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114329

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The effects of the deliberate hydrogenation of GaN were investigated for heteroepitaxial layers grown by metalorganic chemical vapor deposition. The GaN layers were either Mg‐doped,p‐type after thermal activation, or Si‐doped,ntype. Elemental depth profiles from secondary ion mass spectroscopy reveal a striking contrast after a deuteration at 600 °C: the deuterium concentration in Mg‐doped GaN is ∼1019cm−3while there is no detectable deuterium incorporation in then‐type material. Variable temperature Hall effect measurements provide the most direct evidence to date for Mg–H complex formation with the decrease in the hole concentration upon hydrogenation accompanied by an increase in the hole Hall mobility. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114330

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Spectroscopic ellipsometry measurements have been performed during the preparation of hydrogenated amorphous siliconp‐i‐nsolar cells in the SnO2:F/p‐i‐n/Cr configuration. Postdeposition data analysis yields the evolution of bulk, surface roughness, and interface layer thicknesses with ∼0.2 A˚ sensitivity. In addition, the dielectric functions and optical gaps of thep‐,i‐, andn‐layers are determined in the analysis. With the real time measurement approach, the layer properties are determined in the actual device configuration, rather than being inferred indirectly from studies of thick film counterparts. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114287

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report evidence for quasicontinuous optical gain in CdS quantum dots fabricated by the sol‐gel process and embedded in glass. The gain spectra are obtained using the pump and probe technique and nanosecond (quasiresonant) excitation at 11 K. The dots are in the intermediate quantum confinement regime and the concentration of CdS is relatively high. The gain, which is spectrally broad, develops on the low energy side of the absorption band edge. The reason why the gain region is broad is not only the size distribution of the dots, but also the nature of the gain, which originates from the recombination of several excited levels between two and one electron‐hole pairs states (i.e., biexciton to exciton). The maximum measured gain reaches 200 cm−1at 11 K and 17 cm−1at 170 K. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114288

出版商:AIP    

年代:1995

数据来源: AIP