Growth behavior of (C₂H₅)₂GaCl and AsH₃ based GaAs: low reactor pressure and temperatures

Abstract

Alternative metalorganic precursors can often yield improvements in the purity or changes in the growth behavior of the epitaxial layer. Diethyl gallium chloride ((C2H5)2GaCl or DEGaCl) belongs to this class of source molecules and has been used in the selective area growth of GaAs. Selectively grown submicron and quantum-sized structures, as well as the atomic layer epitaxy (ALE) of GaAs, have been demonstrated using the DEGaCl growth chemistry. This paper presents the growth characteristics of DEGaCl over a wide range of conventional growth conditions. The growth behavior and the impurity incorporation at both low growth temperatures (400-800°C) and low reaction pressures (10-78 Torr) have been investigated. The GaAs growth rate appears to be relatively independent of temperature at high reactor pressures and temperatures. The growth efficiency was, however, reduced from that found with (CH3)3Ga within the same reactor. Carbon and silicon were the major impurities in the epitaxial GaAs. The carbon concentration increases with decreasing growth temperature. The silicon depth profiles, obtained from low growth temperature samples, indicate an apparent surface segregation of Si during the growth. The Si concentration increases towards the sample surface eventually reaching a plateau, after which uniform doping is observed. The magnitude of the Si concentration within this plateau region increases with decreasing growth temperature. Electrical measurements indicate that the Si in these samples is either electrically inactive or highly compensated by the carbon acceptors. © 1992.