摘要:

We report the first pulse width study of the various morphological changes and bulk phase transitions of single crystal silicon irradiated by 1‐&mgr;m pulses of 4–260‐ps duration. In particular, we find that amorphous silicon is formed from the melt contrary to published expectations, but only for pulse widths less than 10 ps. We also find that the single shot melting threshold is pulse width dependent. Additionally, we observe the growth of multishot damage and of periodic ripple patterns with pulses as short as 4 ps.

ISSN:0003-6951    

DOI:10.1063/1.94977

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

A new photoconductor device structure is described utilizing a heterojunction contact which incorporates a higher band‐gap HgCdTe alloy between the metal contact and the normal band‐gap photoconductor. A theoretical treatment of the heterojunction contact photoconductor (HCP) device shows that carrier sweepout can be virtually eliminated; the calculations predict elimination of ‘‘saturation’’ of responsivity and a very large increase in responsivity. HCP devices were fabricated; experimental results verified the theory in several ways. A responsivity was measured at 80 K of about 450 000 V/W at 30 V/cm and over 1 500 000 V/W at 125 V/cm.

ISSN:0003-6951    

DOI:10.1063/1.94978

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

Ion implantation of electrically active dopants in silicon lowers the activation energy measured in crystallization growth velocity studies. Evidence indicates that this change is due to an electronic effect, arising from the charging of dangling bonds which produces a shift in the Fermi level on both sides of the amorphous‐crystalline interface. The difference in the shifts of the Fermi levels in the bulk amorphous and crystalline Si is identified as being equal to the change in activation energy. We find the negatively and positively charged dangling bond states to be separated by approximately 0.35 eV, and roughly centered about midgap.

ISSN:0003-6951    

DOI:10.1063/1.94979

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

The effects of strong electric fields, up to 4×105V/cm, on the electron emission from the GaAs dominant midgap levels EL2 and EL0 were investigated by employing differential capacitance transients on GaAs‐Au Schottky diodes. It was found that, in diodes with normal reverse bias characteristics, both levels exhibited a small field enhancement of electron emission, well within the range of the Poole–Frenkel effect. In contrast, very pronounced ‘‘apparent’’ electric field effects were observed in diodes with large reverse bias current. Thus, the conflicting reported results on the magnitude of the field enhancement of the electron emission from EL2 must be attributed to the characteristics of the Schottky diodes employed rather than to those of EL2.

ISSN:0003-6951    

DOI:10.1063/1.94980

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

Single‐crystal multilayers of the dilute magnetic semiconductor Cd1−xMnxTe (x∼0.2) alternating with CdTe have been successfully grown for the first time using the molecular beam epitaxy technique. Four sets of superlattices have been prepared consisting of 14, 60, 90, and 240 double layers of average thickness 460, 140, 75, and 37 A˚, respectively. Each set consists of two samples grown simultaneously using 7×15×1‐mm thick (0001) sapphire substrates onto which 5.0‐&mgr;m‐thick CdTe buffer layers were first deposited. X‐ray diffraction techniques were employed to verify that epitaxy had been achieved and to obtain the average lattice constant of each of the multilayer structures. X‐ray diffraction satellites were observed on both sides of the (111) diffraction peak of the superlattices composed of 14 and 60 alternating layers, respectively, which allowed an accurate estimate of the superlattice period, or double‐layer thickness, for these samples. Results of UV reflectance studies and photoluminescence experiments at liquid nitrogen temperatures are also presented and discussed.

ISSN:0003-6951    

DOI:10.1063/1.94981

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

This letter reports a technique of encapsulated annealing in an arsine ambient which is shown to provide better surface protection for GaAs against thermal degradation than either encapsulation alone or capless annealing in arsine.

ISSN:0003-6951    

DOI:10.1063/1.94982

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

It is shown that in semiconductor superlattices slight fluctuations in the layer thicknesses and alloy compositions are likely to cause strong localization of electronic states. Such localization will hinder miniband formation or band folding expected in an ideal superlattice. The localization tendency can be substantially reduced by decreasing the barrier thickness and/or potential barrier height.

ISSN:0003-6951    

DOI:10.1063/1.94983

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

We have investigated the dependence of the substrate temperature at which the transition from amorphous to polycrystalline state occurs, on the types of substrate, deposition conditions, and impurities. When crystallization is produced by annealing of an amorphous film already formed, the crystallization temperature is 600 °C when annealed under UHV, and higher when exposed to air prior to annealing. The increase is due to the necessity of out diffusion of trapped impurities introduced through the voids during exposure.

ISSN:0003-6951    

DOI:10.1063/1.95002

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

An adjustable metal‐air‐semiconductor capacitor was fabricated using a Pb disk suspended 1700–3600 A˚ above ann‐type Si ⟨111⟩ surface. Experimental differential capacitance versus voltage and differential conductance versus voltage curves are similar to those previously obtained for metal‐oxide‐semiconductor capacitors.

ISSN:0003-6951    

DOI:10.1063/1.95003

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

The capability to measure atom densities of1H,2H, and4He in HgCdTe and CdTe above about 1018cm−3in background‐subtracted cesium beam secondary ion mass spectrometry profiles has been demonstrated using ion implantation and implanted fluences. Range parameters are determined for ion energies between 150 and 300 keV. Projected ranges for1H are slightly greater than those for2H in both HgCdTe and CdTe. Hydrogen ion ranges are about 0.75 &mgr;m/100 keV of energy in both materials, and the third moment of the depth distributions is about −2.1.

ISSN:0003-6951    

DOI:10.1063/1.95004

出版商:AIP    

年代:1984

数据来源: AIP