摘要:

Surface modifications of silicon induced by electron cyclotron resonance (ECR) etching with CF4is studied using x‐ray photoemission spectroscopy and Raman scattering techniques. It is shown that a silicon sample etched by ECR exhibits a thinner surface residual layer compared to those exposed to reactive ion etching (RIE) or hybrid ECR/RIE. Evidence of plasma‐induced structural disorder in the silicon surface was only observed in the RIE‐etched sample.

ISSN:0003-6951    

DOI:10.1063/1.103607

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The room‐temperature operations of an InGaAsP double‐heterostructure (DH) laser emitting at 1.55 &mgr;m on a Si substrate is reported. A pulsed threshold current as low as 46 mA has been measured for a ridge waveguide laser with a 4 &mgr;m strip width and a 200 &mgr;m cavity length. This successful laser operation is due to the high crystalline quality of the DH structure with full width at half maximum of x‐ray rocking curves as low as 110 arcsec grown on a Si substrate by the organometallic vapor phase epitaxy/vapor mixing epitaxy hybrid method. A correlation between the optical property of an InGaAsP DH and its crystalline quality is also discussed.

ISSN:0003-6951    

DOI:10.1063/1.103608

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Heavily phosphorus‐doped polycrystalline silicon films (n+poly‐Si) were etched in a pure chlorine plasma using an ultraclean electron cyclotron resonance etcher. Compared against undoped polycrystalline etching, horizontal etch rates were too high to allow anisotropic etching ofn+poly‐Si. With the addition of more than about 10% N2, highly anisotropic etches ofn+poly‐Si can be obtained simultaneously with selectivities as high as 160 to SiO2in a 4 mTorr plasma. These results are significant to lower submicron fabrication. X‐ray photoelectron spectroscopy studies show that Si—N bonds are formed on then+poly‐Si surface during etching and it is proposed that this layer protects the sidewall against Cl radicals in a N2/Cl2plasma. The suppression of SiO2etching by O2addition to a N2/Cl2plasma has also been demonstrated.

ISSN:0003-6951    

DOI:10.1063/1.103609

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The existence of offset timet0for the Ge deposition is found at the initial stage of Ge epitaxial growth on the Si(100) surface. Thet0is measured for various GeH4pressures and Si surface conditions. From this investigation, it was determined that thet0corresponded to the period for the reduction reaction of surface native Si oxide. It was concluded that the two surface SixO molecules were reduced by one GeH4molecule.

ISSN:0003-6951    

DOI:10.1063/1.104248

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Significant improvements in silicon solar cell performance are reported using an improved high‐efficiency silicon solar cell structure. This structure overcomes deficiencies in an earlier structure by locally diffusing boron into contact areas at the rear of the cells. Terrestrial energy conversion efficiencies up to 24% are reported for silicon cells for the first time. Air Mass 0 efficiencies lie in the 20–21% range, the first silicon cells to exceed 20% efficiency under space illumination.

ISSN:0003-6951    

DOI:10.1063/1.103610

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

&bgr;‐SiC is grown on a silicon substrate by the chemical vapor deposition method using the SiH2Cl2/i‐C4H10/H2/HCl gas system. Stoichiometric &bgr;‐SiC films are obtained with high growth rate at a low temperature of 900 °C. Highly (111) oriented &bgr;‐SiC polycrystal is grown on a Si(111) substrate. Moreover, using the above‐mentioned gas system, &bgr;‐SiC selective growth is attained on a Si substrate, with no nucleation on the SiO2area. This letter discusses thei‐C4H10effects and selective growth condition.

ISSN:0003-6951    

DOI:10.1063/1.103611

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We demonstrate for the first time that a quantum well infrared photodetector based on bound‐to‐continuum state intersubband transitions can have a photoconductive gain much greater than unity similar to extrinsic photoconductors. An optical gaing=8.1 was determined by comparing the optical absorption, responsivity, and noise characteristics of two multiquantum well detectors which were identical in every respect except for having a different number of periods (2 and 20). The results suggest that since the photocarrier lifetime &tgr;Lis not transit time limited, detector optimization to increase &tgr;Lor optical coupling can be expected to lead to an improved detectivityD*.

ISSN:0003-6951    

DOI:10.1063/1.103612

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We investigate a morphological instability that causes an InGaAs/InP multiquantum well structure grown on a vicinal (001) InP surface to spontaneously evolve into an array of InGaAs quasi‐one‐dimensional filaments buried in an InP matrix. To explain this behavior, we propose a step‐flow growth model involving different lateral growth velocities for heteroepitaxy and homoepitaxy. A computer simulation based on the model agrees closely with the experiment.

ISSN:0003-6951    

DOI:10.1063/1.103613

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The difference in the melting temperature of unrelaxed and relaxed amorphous silicon has been determined by measuring the energy density threshold for surface melting during nanosecond laser irradiation (&lgr;=347 nm). The melting onset was detected by time‐resolved reflectivity technique. Using particular samples in which a surface unrelaxed layer was generated by reimplanting a 400‐nm‐thick relaxed amorphous Si (a‐Si) the difference in the melting temperature has been determined independently of the thermal properties of thea‐Si. The melting temperature of relaxeda‐Si resulted to be only 3.9% higher than that of unrelaxeda‐Si, while on the basis of calorimetric data an ∼14% difference was expected. The reasons for this discrepancy are discussed. In addition a 24% increase in the product of thermal conductivity and specific heat ofa‐Si upon relaxation has been found.

ISSN:0003-6951    

DOI:10.1063/1.103614

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The reaction between Cu and TiSi2is studied with and without barriers, Cu being used for interconnect and TiSi2as the gate silicide for the metal‐oxide‐semiconductor devices. The barriers include Ta, TiN, and W. Without a barrier, Cu reacts with TiSi2below 300 °C, forming Cu silicides. An improvement in thermal stability by 50–100 °C is obtained using the barriers, with TiN/Ti being the most effective. A combined use of these barriers, with a final structure of Ta/Cu/Ta/W/TiN/Ti/TiSi2/Si, suppresses the Cu‐TiSi2reaction until above 600 °C. The reaction mechanisms involved, and their relation with the reactions between Cu and other silicides, are discussed.

ISSN:0003-6951    

DOI:10.1063/1.104249

出版商:AIP    

年代:1990

数据来源: AIP