摘要:

Optoelectrical properties of a heterojunction consisting ofp‐type hydrogenated amorphous silicon (a‐Si:H) onn‐type crystalline silicon (c‐Si) have been investigated by measuring current–voltage and capacitance–voltage characteristics and the temperature dependence of the dark current. It was found that the hole injection fromn‐typec‐Si intop‐typea‐Si:H depended mainly on control of the impurity concentration ina‐Si:H doped with boron at the junction interface. The results obtained for the dark current and photocurrent (with 100 1×illumination) were 7.3 nA cm−2and 41 &mgr;A cm−2, respectively, at an applied voltage of 5 V. These results hold promise for applications to a silicon vidicon target without a diode array.

ISSN:0003-6951    

DOI:10.1063/1.95212

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

Oxygen is the dominant impurity in pulled silicon. At 450 °C, thermal donors form in oxygen rich silicon. Using deep level transient spectroscopy, this donor is found to have an energy level of 0.142 eV below the conduction band at zero electric field, exhibiting behavior consistent with the Poole–Frenkel field assisted electron emission process. Using deep level transient spectroscopy in conjunction with calibrated uniaxial stress, we have determined the symmetry of the neutral 450 °C oxygen donor complex to beD2d. Possible models for the oxygen donor complex are presented which are consistent with the observed symmetry and with previous experiments.

ISSN:0003-6951    

DOI:10.1063/1.95213

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

Optical properties of GaAs bulk layers and (Al,Ga)As/GaAs quantum wells with well sizes of 80, 100, and 200 A˚ have been studied. The structures were grown on (100) oriented Ga doped Ge substrates using molecular beam epitaxy. In contrast to earlier less successful attempts to grow polar semiconductors on nonpolar (100) substrates, the structures prepared in this study had good surface morphologies across the entire substrate and seemed relatively free of nonradiative traps. In bulk and quantum well structures, bound excition and donor‐acceptor transitions were observed. The luminescent intensity at 2 K was comparable to that of similar structures grown on GaAs substrates and dominated by donor‐acceptor (Ge0Ga‐Ge0As) transitions. The ability to successfully grow polar semiconductors on (100) nonpolar semiconductors should provide many opportunities in hybrid and heterojunction device applications.

ISSN:0003-6951    

DOI:10.1063/1.95214

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

We have investigated the effect of residual carbon concentration on the threshold voltage (VT) of field‐effect transistors (FET’s) fabricated by direct ion implantation with undoped semi‐insulating liquid encapsulated Czochralski GaAs. The results show the direct dependence ofVTon the carbon concentration. For depletion‐mode FET’s, ‖VT‖ decreases linearly as the carbon concentration increases, with a variation of 185 mV inVTfor a 1×1016cm−3change of carbon concentration, consistent with theory. Our results also show that the radial carbon concentration across crystals is uniform to within about ±6×1014cm−3; however, the carbon concentration invariably decreases toward the tail of the crystals by 40% or more. As a result, ‖VT‖ tends to increase toward the tail of the crystals.

ISSN:0003-6951    

DOI:10.1063/1.95215

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

Change of the surface density of the midgap level (EL2 or EL0) in bulk GaAs by heat treatment was studied on horizontal Bridgman (HB) and liquid encapsulated Czochralski (LEC) grown GaAs by changing the capping materials (Si3N4, SiO2, GaAs) and the ambient (H2, vaccum). Decrease of the surface density of the midgap level was prevented on HB GaAs by capping with Si3N4, SiO2or GaAs, whereas it could not on LEC GaAs when it is capped with Si3N4or SiO2. Emission rates of the midgap level in LEC GaAs changed by the heat treatment but it did not for HB GaAs. These results support that the midgap levels in HB and LEC GaAs are due to different point defects (EL2 or EL0).

ISSN:0003-6951    

DOI:10.1063/1.95216

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

The diffusion of As in polycrystalline silicon films subjected to rapid thermal annealing has been studied using sheet resistance and Rutherford backscattering. The polycrystalline Si films were deposited on oxidized silicon wafers, implanted with As, and annealed with a Varian IA‐200 isothermal annealer. Infrared radiation from a resistively heated sheet of graphite heats the wafer, in a vacuum, to temperatures >1000 °C for times on the order of a few seconds. The rate of diffusion and rate of loss of As from the polycrystalline Si is much faster than the diffusion rate and loss rate in single crystal Si annealed with identical conditions. Diffusion prior to grain growth agrees with previously reported results for As in polycrystalline Si. However, grain growth appears to enhance As diffusion.

ISSN:0003-6951    

DOI:10.1063/1.95217

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

We present results of a new model to describe the dependence of the room‐temperature steady‐state photoconductivity in amorphous silicon alloys upon the position of the dark Fermi level. This dependence is a consequence of both a change in the recombination path and dopant‐created gap states. We also demonstrate the relationship between the power dependence of photoconductivity and dark Fermi level position and show that as a result of space charge neutrality, this dependence can be related to a characteristic energy slope of the density of states only in the absence of injected charge or dopants. Moreover, in agreement with recent experimental data, we show that our model predicts a power dependence of less than 0.5 for high‐intensity illumination onn‐type amorphous silicon.

ISSN:0003-6951    

DOI:10.1063/1.95218

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

Alloying of Al‐1% Si integrated‐circuit metallization by 5‐s heat pulses at temperatures ranging from 490 to 540 °C was compared to standard 30‐min furnace alloying at 425 °C. Hillocks were present on all furnace‐alloyed samples, but were absent from all heat‐pulse‐alloyed samples. (Al‐Si)/n+Si contact resistances equivalent to those obtained with furnace alloying were obtained for heat‐pulse temperatures ranging from 505 to 525 °C. Diode leakage characteristics equal to those obtained with furnace alloying were obtained for heat‐pulse temperatures up to 520 °C. Effective radiation‐damage annealing was accomplished by a heat pulse in forming gas at 500 °C.

ISSN:0003-6951    

DOI:10.1063/1.95219

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

The optical band edge of reactively sputtered CuxS films has been determined to be 1.18±0.03 eV using a technique in which the conductance of the films with respect to the wavelength of the incident light was measured. These results were found to confirm optical absorption data on CuxS films. Also, the efficiency of a 6.0% solar cell which was made using this sputtering technique is reported.

ISSN:0003-6951    

DOI:10.1063/1.95220

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

UV radiation from an ArF laser has been used to perform large‐area etching of single‐crystal GaAs. The process is based on photochemical production of methyl or trifluoromethyl, and bromine radicals. The etching is anisotropic and features <1 &mgr;m have been made.

ISSN:0003-6951    

DOI:10.1063/1.95221

出版商:AIP    

年代:1984

数据来源: AIP