The n-type doping of [formula omitted] and growth of two-dimensional electron gas structures with DEAlH-NMe3 as Al source

Abstract

The n-type doping of AlGaAs with disilane (Si2H6) was investigated. To overcome the known disadvantages of the commonly used group III precursors, diethylaluminiumhydride-trimethylaminadduct (DEAlH-NMe3) as Al source and triethylgallium (TEGa) as Ga source were used. The dependence of the carrier concentration on the Si2H6 partial pressure was studied. A weak dependence on the substrate orientation was found. Temperature dependent Hall measurements gave no indication to DX centers. With low frequency noise measurements a deep level with an activation energy of 0.27 eV was detected. The electrical properties gave a hint to H passivation of the DX center and an AlO complex acting as deep level. Superlattices were grown to find growth parameters for the growth of abrupt GaAsAlGaAs interfaces. As an application of the doping studies and optimization of the heterointerfaces, a two-dimensional electron gas structure was grown. A room temperature mobility of μ300 = 5 300 cm2/V·s and at 77 K μ77 = 52 000 cm2/V·s with a corresponding sheet carrier concentration of ns = 1 × 1012 cm−2 was achieved.