摘要:

The quaternary III–V compound semiconductor GaInAsP is an important material for many optoelectronic devices, the surface of which generally needs to be passivated in the fabrication of such devices. Thus understanding the surface chemistry and monitoring the surface band gap states after oxidation and sulphur passivation have become necessary. Further, understanding the effect of ion bombardment on the GaInAsP surface during dielectric deposition is also of importance for device fabrication. In this study, quaternary GaInAsP(100) surfaces were subjected to UV/ozone and wet chemical treatments, dilute HF etching, sulfur passivation, and Ar ion bombardment. The composition and the relative movement of the surface Fermi level(EFs)of the surfaces were measured by x-ray photoemission spectroscopy (XPS) after oxidation, HF etching, sulfur passivation, and ion bombardment of surfaces. It was found that oxidation by ozone exposure formed multiple oxide phases of all the constituent elements. Both HF etching and sulfur passivation treatments were effective in generating surfaces having almost no oxide. It was also found that while sulfur passivation combined with an ultrahigh vacuum annealing at 300 °C reduced the surface band bending onn-type GaInAsP(100), it invertedp-type GaInAsP ton-type. AnL-edge absorption spectrum of the sulfur passivated surface confirmed the presence of a sulfur layer. Further, it was found that an Ar+ion bombardment pins theEFsnear the midgap for bothn- andp-type GaInAsP surfaces. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364315

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

An approach to synchronous single-electron digital circuits is described in which only one clocking signal is required. Such designs may facilitate the development of clock distribution methods with the excellent scaling properties needed if a practical single-electronics technology is ever to be realized.

ISSN:0021-8979    

DOI:10.1063/1.364316

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A molecular beam epitaxy grown wavelength tunable GaAsp+-ihomojunction interfacial work-function internal photoemission far-infrared detector is developed. The multilayer(p+-i-p+-i-&ellip;) detector structures consist of 2, 5, and 10 emitter layers. Experimental results are explained in terms of the number of emitter layers and the doping concentrations of the emitter layer. A detector with 10 multilayers and an emitter layer doping concentration(Ne)of3×1018cm−3shows a current responsivity of 2 A/W, an effective quantum efficiency of 9.2&percent; (at 26.3&mgr;m) with a cutoff wavelength of 85&mgr;and the noise equivalent power of 2.18×10−12W/Hzat 4.2 K. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364356

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

When Si layers were grown on Ge(100) by alternatingSiH2Cl2gas exposure and irradiation with synchrotron radiation, bistable growth occurred at temperatures (i) below 400 °C (0.21 Å/cycle) and (ii) between 470 and 530 °C (0.42 Å/cycle). The growth rate saturated for bothSiH2Cl2exposures and synchrotron-radiation (SR) irradiation time. In regime (i) chemisorption and photon-stimulated desorption of H and Cl atoms on the Si overlayer resulted in Stranski–Krastanov-type growth. In regime (ii) chemisorption on a bare Ge surface, removal of the ligands by photothermal desorption, and enhanced migration of Si adatoms resulted in Volmer–Weber-type growth. Island size increased with increasing SR irradiation time in the exposure-irradiation cycle. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364317

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The influence of the depolarization and exciton-like effect on the photoionization spectra ofn-type quantum wells is studied theoretically employing the local density approximation. A critical discussion of the results obtained by other authors is given. Numerical examples forGaAs/AlGaAsandSi/SiGequantum wells are presented. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364318

出版商:AIP    

年代:1997

数据来源: AIP