摘要:

The presence of hydrogen in HF solutions at a silicon substrate surface is shown to be sufficient to produce a photoluminescent porous silicon layer. The photoluminescence measurements of bubbled and anodized samples show similar spectra when illuminated with UV radiation. This is strong evidence that the hydrogen produced by the anodic silicon dissolution reaction is also responsible for the formation of nanostructures. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119055

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Specular scattering of 3 keV He ions was observed for incidence angles of 2°–6° from GaAs(001). During molecular beam epitaxy, the scattered ion current dropped rapidly upon opening the Ga shutter, showed damped oscillations, and then increased gradually upon closing the shutter. The oscillation periods corresponded to monolayer growth times. Oscillation amplitudes decreased with increasing substrate temperature, indicating a transition to step-flow growth. The oscillations were not a diffraction effect, allowing a quantitative interpretation based on scattering by adatoms and step edges. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119020

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We have studied the dopant redistribution between a chemical beam epitaxy (CBE) grown InGaAsP laser structure and a metalorganic vapor phase epitaxy overgrown InP layer. Secondary ion mass spectroscopy analysis reveals that Zn and Be atoms deeply interdiffuse in the adjacent InP layers for a Zn doping of1018 cm−3and that a fraction of Zn atoms go through the CBE InP and penetrate the laser structure guide layer. We have found that the Zn outdiffusion is significantly suppressed by reducing the Be doping concentration from1018to5×1017 cm−3.As a result, for tensile-strained InGaAsP multiquantum well (MQW) buried-heterostructure (BH) lasers, the threshold current and internal loss decrease from 13 to 9 mA and 15 to10 cm−1by lowering the Be doping, respectively. InAsP MQW BH lasers have an internal loss of5.5 cm−1.©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119053

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

An ensemble Monte Carlo simulation is used to compare high field electron transport in bulk GaN and GaAs. In particular, velocity overshoot and electron transit times are examined. In GaN, we find the steady state velocity of the electrons is the most important factor determining transit time over distances longer than 0.2 &mgr;m. Over shorter distances velocity overshoot effects in GaN at high fields are comparable to those in GaAs. We estimate the minimum transit time across a 1 &mgr;m GaN sample to be about 3.0 ps. Similar calculations for GaAs yield 5.4 ps. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119021

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Si solid state photomultipliers utilize impact ionization of shallow impurity donor levels to create an avalanche multiplication when triggered by a photoexcited hole. The distribution of pulse height from a single photon detection event shows narrow dispersion, which implies that the avalanche multiplication process in these devices is inherently noise-free. We have measured the excess noise factor using two different techniques, digital pulse height analysis and analog noise power measurement. The results demonstrate nearly noise-free avalanche multiplication accomplished in these devices. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119022

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Enhanced electroabsorption, due to field-induced degeneration of light-hole and heavy-hole states, is found in tensile-strainedGa0.53In0.47Asquantum wells withAl0.48In0.52Asbarriers. This behavior seems to be specific for the AlGaInAs material system, where the Stark shift is dominated by heavy holes rather than by electrons. The effect, predicted theoretically by band structure calculations, is verified by differential electrotransmission experiments at 300 and 77 K. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119023

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A monolithic vertical cavity bistable device based on the InGaAlAs system has been grown by low pressure metalorganic vapor phase epitaxy in a single run. First observation of all-optical bistability is reported in this new monolithic structure, with a contrast of 15:1 and a threshold power of less than 300 &mgr;W. X-ray diffraction and reflectivity measurements confirmed the high crystallographic and optical qualities of the material. This result shows that the InGaAlAs system is well suited to the fabrication of vertical cavity devices in the optical communication wavelength range. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119024

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

GaAsN layers with good structural quality and surface morphology have been successfully grown on a GaAs substrate using atmospheric pressure metal organic vapor phase epitaxy. A new combination of precursors namely, dimethylhydrazine for nitrogen and tertiarybutylarsine instead of conventional arsine for arsenic, greatly facilitated growths at temperatures as low as 500 °C. Layers with N content as high as 3&percent; and corresponding to room temperature photoluminescence (PL) peak wavelength of 1.17 &mgr;m (1.064 eV) have been obtained. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119025

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We report experimental, room temperature data showing real space transfer in a heterostructure which can support the movement of electrons over a barrier in both directions between two channels. Real space transfer occurs between two channels connected in parallel in a three-gate transistor, which has been developed to interrogate the channel populations. Results are presented that demonstrate real space transfer in a heterostructure which features a 2.5:1 mobility ratio between channels. This heterostructure is designed for use in a velocity modulation transistor, which requires reciprocal, gate-assisted transfer between two channels of differing mobilities. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119026

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Peak current densities two times higher than the best values reported for GaAs-based resonant tunneling diode (RTD) structures have been obtained from metal-organic chemical-vapor deposition (MOCVD)-grown deep-quantum-well strained-layerIn0.3Ga0.7As/Al0.8Ga0.2AsRTDs. By growing on nominally exact (100)+/−0.1°GaAs substrates, we have been able to obtain smooth interfaces between the strained-layerIn0.3Ga0.7Asquantum well andAl0.8Ga0.2Asbarriers, which, in turn, enabled us to benefit from resonant tunneling through thesecondresonant energy level ofIn0.3Ga0.7As/Al0.8Ga0.2Asstructures. Peak current densities in excess of300 kA/cm2,and peak-to-valley current ratios as high as 3:1, at 300 K, have been obtained from structures with 14-Å-thick barriers and a 57-Å-thick well. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119027

出版商:AIP    

年代:1997

数据来源: AIP