分子束外延生长GaAs/Si异质结电学特性的研究

A STUDY OF ELECTRONIC CHARACTERIZATION IN MOLECULAR BEAM EPITAXIALLY GROWN GaAs ON Si

利用样品Au-GaAs/p-Si的肖特基势垒二极管特性和深能级瞬态谱(DCTS),研究Si衬底上分子束外延生长的GaAs异质结的电学特性。I-V特性表明样品有大的漏电流存在,而快速热退火处理则能使样品I-V特性得以改善,并接近半绝缘GaAs(S.I.GaAs)上生长的Au-GaAs/S.I.GaAs样品的特性,它的来源不是热电子发射或产生-复合电流所引起,而可归结于缺陷参与的隧穿机制,它可通过快速热退火处理得以减小。DCTS谱表明在样品中可观察到Ec-0.41eV和Ec-0.57eV两个电子陷阱,前者可能是GaAs/Si界面附近处的缺陷态,后者则与分子束外延生长的GaAs中的固有缺陷M,有关。

The electronic characteristics of GaAs grown on Si by molecular beam epitaxy(MBE) has been examined by studying the diode characteristics and deep level transient spectroscopy (DLTS) of Schottky barriers. l-V characteristics of samples show the existence large leakage current. Post-growth rapid thermal annealing(RTA)has been found to be able to significantly improve the diode behaviour. The reverse current in the as-grown material shows a very weak temperature dependence, indicating that its origin is not thermoionic emission or generation-recombination currents. We think that a large part of this current is due to defect-assisted tunneling, which is reduced by RTA. DLTS spectra show that Ec-0.41eV and Ec-0.57eV electron traps are observable. The former is located near the GaAs-Si interface probably, the latter relates to the well-known electron trap M5 typical of MBE GaAs.