摘要:

A thermodynamic first‐principles theory of stability, including charge transfer, elastic forces, and atomic relaxations reveals the physical origins of stable and metastable ordering in bulk and epitaxial semiconductor alloys and superlattices.

ISSN:0003-6951    

DOI:10.1063/1.102695

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Dilute CxSi1−xepitaxial films have been grown on Si(100) by remote plasma‐enhanced chemical vapor deposition. Carbon concentrations of ∼3 at.% have been achieved at a growth temperature of 725 °C. No evidence for the formation or precipitation of SiC was found using x‐ray diffraction and transmission electron microscopy.

ISSN:0003-6951    

DOI:10.1063/1.102696

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Centimeter‐size single‐crystal InP or GaAs wafers have been fused together entirely, face to face or side by side, after a heat treatment in a graphite/quartz reactor which can press the wafers together through differential thermal expansion. Diodes formed by fusingp‐ andn‐type wafers showed normal current‐voltage characteristics and light emission. Fusion between lattice‐mismatched wafers (i.e., InP and GaAs) has also been demonstrated.

ISSN:0003-6951    

DOI:10.1063/1.102697

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Data are presented demonstrating room‐temperature operation of AlxGa1−xAs‐GaAs vertical‐cavity surface‐emitting lasers grown on Si substrates. The device structures are grown using molecular beam epitaxy and a grown‐in quarter‐wave AlAs‐GaAs stack is used as then‐side reflector and a nonalloyed Ag dot used as thep‐side reflector/contact. Pulsed threshold currents of ∼125 mA are obtained for a 15‐&mgr;m‐diam device.

ISSN:0003-6951    

DOI:10.1063/1.102698

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Scanning tunneling microscopy on cleaved Si(111) surfaces reveals stress‐induced microstructures with two types of terraces: triangular‐shaped terraces and long and narrow terraces with parallel [112¯] oriented steps, which is contrary to the previous observation [1¯1¯2] steps. Dimer rows in Si(111) 2×1 structures are found on the triangular terraces. On the parallel‐stepped terraces, rows run in the [112¯] direction and their separation was appreciably smaller than that of the dimer rows in the 2×1 structure. A new model for this structure is proposed.

ISSN:0003-6951    

DOI:10.1063/1.102699

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Highly strained In0.66Ga0.34As/In0.30Al0.70As multiquantum wells (MQWs) are successfully grown on (001)InP substrates by moleular beam epitaxy. Good crystal quality in the strained MQWs is confirmed by clear excitonic peaks and sharp photoluminescence spectra. Intersubband absorption at a wavelength as short as 3.1 &mgr;m was obtained for the first time in uniformly Si‐doped strained MQWs.

ISSN:0003-6951    

DOI:10.1063/1.102700

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have studied the mechanism of increased etch rate induced in InP substrates by focused Ga ion implantation and Cl2etching. We cannot account for the depth of surface steps formed in this process with a purely kinetic mechanism. The preferential etching of implanted areas is attributed instead to local modification or removal of native oxides from the surface of InP. The thin oxide layer effectively protects the substrate and inhibits Cl2etching. Consistent with the thermodynamic prediction, a cleaned InP(100) surface is etched by Cl2(5×10−4Torr) with a rate of approximately 1000 A˚/min at 200 °C. Surface steps as deep as 3 &mgr;m have been reproducibly prepared using an oxide mask believed to be approximately 20 A˚ thick. In the etching process, any substrate damage caused by the Ga beam writing is completely removed. The oxide mask, which can be patterned on a very fine scale by energetic particle bombardment, provides a new avenue forinsituprocessing of InP.

ISSN:0003-6951    

DOI:10.1063/1.102701

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Zn and an unidentified acceptor species, labeledA1, are the only residual acceptors that have been observed in a wide variety of undoped high‐purity InP samples grown by metalorganic chemical vapor deposition. Carbon is not incorporated at detectable concentrations as a residual acceptor in metalorganic chemical vapor deposited InP. However, the longitudinal and transverse optical phonon replicas of the free‐exciton recombination occur at the same energy as the donor/conduction band‐to‐acceptor peaks for C acceptors in low‐temperature photoluminescence spectra. Since these replicas are usually present in photoluminescence spectra measured under moderate or high optical excitation, care must be exercised so that these peaks are not misinterpreted as C‐related transitions.

ISSN:0003-6951    

DOI:10.1063/1.102702

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Studies of a polydiacetylene negative electron beam resist have been made in a scanning tunneling microscope operated in vacuum at pressures in the 10−8Torr range. The resist can be imaged if it is applied as a thin film to a conductive flat substrate and the tip bias voltage is chosen appropriately. An exposure threshold energy close to 8 eV has been observed for the formation of raised features in the resist. A minimum feature size of about 20 nm has been measured when written at an energy just above the exposure threshold. Details of the necessary substrate preparation are described together with the operation of the scanning tunneling microscope during imaging and exposure. The exposure dose is applied by raising the bias voltage for a specific time while keeping the tip‐sample current constant which has permitted insights into the mechanisms of the resist exposure.

ISSN:0003-6951    

DOI:10.1063/1.102703

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

It is demonstrated that strain‐induced electric fields in [111] growth‐axis strained‐layer structures can be used to induce a two‐dimensional electron gas without the necessity of modulation doping. A simple analytic expression is derived for the density of the two‐dimensional electron gas. The density has a simple linear relationship to the strain‐induced electric fields. The calculation predicts that two‐dimensional densities in the range 1011–1012cm−2should be easily realized in strained‐layer structures. Results are calculated for a variety of material systems.

ISSN:0003-6951    

DOI:10.1063/1.102704

出版商:AIP    

年代:1990

数据来源: AIP