摘要:

Fast oxidation of amorphous (a)Si1−xGex:H by interfacial reaction withSnO2was observed at the temperature range of 400–500 °C. The rate of interfacial oxidation was very significant, while a test in a dryO2ambient at the same temperatures showed no oxidation ofSi1−xGex:H beyond the native oxide. The interfacial reaction of theSiGe:H/SnO2/glass system resulted in a layered structure of silicon oxide, tin oxide, and &bgr;‐Sn at theSiGe/SnO2interface. The extent of the interfacial reaction was found to depend on the Ge content in theSi1−xGex:H films; after annealing, the resultant silicon oxide layer is thicker for the Si‐rich SiGe layer than for the Ge‐rich composition. On the other hand, theSnO2layer was totally reduced by ana‐Ge:H top layer after a 1 h, 500 °C annealing procedure. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114638

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Electrical homogeneity is an essential requirement for semi‐insulating (SI)InP:Fe wafers. A method is presented to measure the spatial distribution of resistivity at room temperature via the photorefractive effect. The experimental conditions are presented and discussed. The potential of the method is demonstrated by applying it to SI liquid encapsulated Czochralski grown material. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114639

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Low‐temperature,T<90 K, illumination transfers transparent, single crystals of AlSb doped with Se to a metastable state characterized by a high optical absorption approaching 200 cm−1. The enhanced absorption spectrum extends from 0.1 to 1.5 eV and consists of a double band structure with peaks at 0.2 and 0.5 eV. It is induced by photons with a threshold energy of about 1 eV. It is persistent, i.e., it shows no measurable decay after switching off the excitation. The low absorption state is thermally recovered at 100 K. The persistent absorption is a manifestation of a DX‐type bi‐stability of the Se donor. The 0.2 and 0.5 bands are, respectively, due to the photoionization of electrons from the metastable hydrogenic donor level toX1andX3conduction band minima. A large binding energy of the Se donor is essential for the observation of persistent absorption and a lack of any free‐electron related effects. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114640

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

An investigation of the fast diffusion of Si in GaAs from deposited surface layers oxidized in an Ar/H2O ambient indicates excess As, formed by oxidation of Ga originating from the substrate, is responsible for the enhanced diffusion of Si into the substrate. The formation of the SiO2on the surface during oxidation prevents loss of the excess As, which accumulates in the remaining Si film. Higher H2O partial pressures during the oxidation produce higher As/Si ratios, resulting in an increase in the Si diffusion depth and concentration. However, then‐type carrier concentration decreases with higher As/Si ratios in the remaining Si layer. A second, nonoxidizing anneal on samples with the SiO2and Si layer removed produced different effects on the carrier concentration, depending on whether As was free to escape from the substrate. The results indicate that excess As related defects such as gallium vacancies are probably responsible for then‐type compensation in the fast diffused samples. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114641

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Monocrystalline GaN(0001) thin films, void of oriented domain structures and associated low‐angle grain boundaries, have been grown via organometallic vapor phase epitaxy (OMVPE) on high‐temperature monocrystalline AlN(0001) buffer layers predeposited on vicinal &agr;(6H)–SiC(0001) wafers using TEG, TEA, and ammonia in a cold wall, vertical, pancake‐style reactor. The surface morphology was smooth, and the PL spectrum showed strong near‐band‐edge emission with a full width at half‐maximum (FWHM) value of 4 meV. The dislocation density within the first 0.5 &mgr;m was ≊1×109cm−2; it decreased substantially with increasing film thickness. Controlledn‐type Si doping of GaN has been achieved for net carrier concentrations ranging from ∼1×1017to 1×1020cm−3. Double‐crystal XRC measurements indicated a FWHM value of 66 arcsec for the GaN(0004) reflection. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114642

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A GaAs/n+‐In0.2Ga0.8As/GaAs doped‐channel field‐effect transistor structure has been fabricated and studied. A typical transistor performance with a threshold voltage of about −3.0 V and transconductance of up to 160 mS/mm is obtained in the lower gate‐source voltage (VGS<−1.0 V) regime. However, for some devices, the three‐terminal‐controlled N‐shaped negative‐differential‐resistance (NDR) behavior is observed at the saturation regime of current–voltage characteristics under higher gate‐source bias (VGS≥−1.0 V) condition. The interesting NDR phenomenon is believed to be attributed to the real‐space transfer and deep‐level electron trapping effect. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114643

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A Bragg reflector consisting of a 25‐period MnZnSSe/ZnSSE Bragg stack is reported. The II–VI semiconductor structure was grown by molecular beam epitaxy on a GaAs (100) epilayer. Structural characterization of the Bragg reflector was performed with double crystal x‐ray diffraction and transmission electron microscopy. These studies indicated that the epitaxial II–VI structure, whose total thickness is about 2150 nm, remains pseudomorphic with the GaAs substrate. The Bragg stack has a maximum reflectance of 81% at 468 nm. This result shows that fabrication of high reflectance mirrors from epitaxial ZnSe‐based II–VI compounds is possible in spite of relatively small refractive index differences between constituent II–VI layers. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114644

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The crystalline structure of GaN epilayers on (0001) SiC substrates has been studied using x‐ray diffraction and transmission microscopy. The films were grown by metalorganic chemical vapor deposition, using AlN buffer layers. X‐ray diffraction measurements show negligible strain in the epilayer, and a long‐range variation in orientation. Transmission electron lattice images show that the AlN buffer layer consists of small crystallites. The nature of the buffer layer and its interfaces with the substrate and the GaN film is discussed. The defect structure of the GaN film away from the substrate consists mostly of threading dislocations with a density of ∼109cm−2. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114645

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report the direct measurement of the intrinsic photocurrent response of both top and back illuminated planar metal–semiconductor–metal structures. We directly observe the temporal dynamics of the hole transport dependence on applied bias and the initial spatial distribution using a near infrared tunable femtosecond light source and electrically biased structures. The increased hole transit time of back illuminated structures can be completely understood in terms of the hole velocity and the initial spatial distribution of the carriers. Additionally, we report the fastest directly measured 50 &mgr;m diameter InGaAs photodetector with a 26 ps full width at half maximum. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114646

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The gettering of ion implanted Au to defects in Si has been studied using Rutherford backscattering and channeling and transmission electron microscopy. Damage from a Si implant anneals into dislocations which can efficiently trap diffusing Au. The damage introduced by a H implant evolves during annealing into cavities which getter close to 100% of the Au, leaving very little Au in solution. This process is driven by the diffusion of a supersaturated solid solution of Au to a favorable sink. The internal surfaces of cavities are the most favorable sink, followed by dislocations and then the Si surface. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114647

出版商:AIP    

年代:1995

数据来源: AIP