THE N-TYPE DOPING OF GAAS/ALXGA1-XAS AND GROWTH OF 2-DIMENSIONAL ELECTRON-GAS STRUCTURES WITH DEALH-NME(3) AS AL SOURCE

The n-type doping of AlGaAs with disilane (Si2H6) was investigated. To overcome the known disadvantages of the commonly used group III precursors, diethylaluminiumhydride-trimethyl aminadduct (DEAIH-NMe,) 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-AIGaAs 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 mu(300) = 5 300 cm(2)/V.s and at 77 K mu(77) = 52 000 cm(2)/V.s with a corresponding sheet carrier concentration of n(s) = 1 x 10(12) cm(-2) was achieved.