摘要:

Bi‐metallic Schottky contacts of Cr‐Al onp‐type Si using a layered structure have been investigated. In these contacts, the thickness of the inner layer in contact with Si was varied, while that of the outer metal layer was kept constant. Our studies indicate that the barrier height changes with the thickness of the inner metal layer. Furthermore, the morphology of our samples was examined with a transmission electron microscope (TEM) which indicates the presence of inhomogeneous mixing of Cr and Al.

ISSN:0003-6951    

DOI:10.1063/1.105946

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We have developed techniques to determine the near‐infrared to near‐ultraviolet dielectric function and optical gap of ultrathin amorphous silicon [a‐Si:(H)] using real‐time spectroscopic ellipsometry during preparation and processing. The techniques have been applied to ∼50 A˚a‐Si:H films prepared by plasma‐enhanced chemical vapor deposition, and to ∼250 A˚ purea‐Si chemically modified by atomic H exposure. For the latter, the time evolution of the bonded H content can be estimated along with the evolution of the gap.

ISSN:0003-6951    

DOI:10.1063/1.105947

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We report a new low‐temperature (<300 °C) process for selective deposition of silicon using time modulated flow of silane into a hydrogen plasma. Time modulated gas flow allows the chemical processes associated with deposition and surface modification or etching to occur sequentially, and be controlled independently, giving an additional degree of freedom to the deposition process. The observed selective deposition is consistent with substrate specific nucleation, and preferential etching of the nuclei during the hydrogen plasma exposure. The application of the selective deposition process to the fabrication of thin‐film transistor structures is also presented.

ISSN:0003-6951    

DOI:10.1063/1.105948

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The spectral dependence of the photocurrent in intrinsic hydrogenated amorphous silicon (a‐Si:H) films was measured in the annealed and light‐soaked states. The photocurrents were modeled using numerical analysis which quantified the recombination in both the bulk as well as at the film surface and glass substrate interface. The results on films, having thicknesses between 1 and 3 &mgr;m, are consistent with thickness independent bulk transport properties and surface and substrate interface recombination velocities of (3–6)×104and (1–2)×106cm/s, respectively.

ISSN:0003-6951    

DOI:10.1063/1.105949

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

An attempt was made to deposit a high thermally stable silicon dioxide (SiO2) film onto InP substrates. The films were grown by rapid thermal, low‐pressure chemical vapor deposition (RT‐LPCVD), using pure oxygen (O2) and 2% diluted silane (SiH4) in argon (Ar) gas sources, in the temperature range of 350–550 °C and pressure range of 3–10 Torr. The SiO2/InP structures were heated, post‐deposition, up to 1000 °C for durations of up to 5 min, resulting in negligible changes in the properties of the SiO2films and a limited SiO2/InP interfacial reaction of about 15 nm thick. The higher the initial deposition temperature of the SiO2the larger was the film compressive stress and the less the degree of densification the film underwent through the post‐deposition heating cycles.

ISSN:0003-6951    

DOI:10.1063/1.105950

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We have calculated the performance of indium phosphide solar cells with lattice matched wide band‐gap In0.52Al0.48As window layers using the PC‐1D computer code. The conversion efficiency ofp+nInP solar cells is improved significantly by the window layer. No improvement is seen forn+pstructures. The improvement in InP cell efficiency was studied as a function of In0.52Al0.48As layer thickness. The use of the window layer improves both the open circuit voltage and short circuit current. For a typical In0.52Al0.48As window layer thickness of 20 nm, the cell efficiency improves in excess of 27% to a value of 18.74%.

ISSN:0003-6951    

DOI:10.1063/1.105951

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We study the instantaneous nonlinear index change in Al0.2Ga0.8As waveguides below the two‐photon absorption edge and find &pgr; phase shifts with 80 pJ, 0.4 ps pulses at wavelengths near 1.6 &mgr;m. These large phase shifts are obtained with less than 1 dB of loss from multiphoton absorption. Our results indicate that AlGaAs waveguides, which have a mature fabrication technology, can be used as compact nonlinear elements in switching and quantum optics applications in the near‐infrared. Further optimization of the waveguide geometry should result in useful nonlinear phase shifts and low losses for pulse energies approaching a picojoule.

ISSN:0003-6951    

DOI:10.1063/1.105952

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

X‐ray experiments are usually seen as a tool for studying large lattice imperfections. We present for the first time experimental evidence obtained from x‐ray measurements that metastable behavior of the EL2 defect in semi‐insulating GaAs can be connected with crystal lattice relaxation. New unexpected results showing change of the lattice state while cooling semi‐insulating GaAs samples in darkness are also reported.

ISSN:0003-6951    

DOI:10.1063/1.105953

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

An unusual fourfold extended dislocation node at a SixGe1−x/Si strained layer interface has been revealed using weak‐beam electron microscopy. A detailed contrast analysis shows that this node structure is the result of the constriction of Lomer–Cottrell dislocations formed by intersecting slip dislocations on {100} and {111} type planes. This mechanism necessitates the glissile behavior of dislocation nodes at the (100) epitaxial interface.

ISSN:0003-6951    

DOI:10.1063/1.105955

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The capability to detect and quantify sulfur at the part‐per‐billion (ppb) concentration level in ultrapure hydrochloric acid rinse solutions used in GaAs wafer fabrication is described. Nonvolatile residues formed from the deposition of nanoliter aliquots of solution onto high purity silicon wafers are analyzed using a high performance CAMECA IMS 4fion microanalyzer. The dynamic SIMS analysis of microdroplet residues is referred to as Microvolume‐SIMS (MV‐SIMS). The Microvolume‐SIMS analyses of two acid solutions are presented. The concentration of total sulfur detected in these solutions was 98 and 650 ppb; both values are below the SEMI specification standard of less than 1300 ppb total sulfur concentration. Despite this, the acid solution containing 650 ppb of total sulfur was responsible for causing an isolation failure halting wafer production. This finding corroborated electrical failure analyses using these same acids.

ISSN:0003-6951    

DOI:10.1063/1.105956

出版商:AIP    

年代:1991

数据来源: AIP