Si-doping of MOVPE grown InP and GaAs by using the liquid Si source ditertiarybutyl silane

The liquid Si-compound ditertiarybutyl silane (DTBSi) has been investigated as a doping source for the metal organic vapour-phase epitaxy (MOVPE) of InP and GaAs using TBP or DTBP and TBAs as less hazardous group-V-sources. For both material systems the measured carrier concentration is directly proportional to the DTBSi/group-III-partial pressure ratio with a slope of unity. Uncompensated n-type InP as well as GaAs layers are achieved up to the 10(18) cm(-3) doping range. Additional calibrated SIMS-studies of InP layers show a coincidence of the Si-concentration in the InP layers with the measured net n-type carrier concentration within the experimental errors. With a reduction of the growth temperature from 610 degrees C to 570 degrees C a significant reduction of the Si-doping efficiency is observed. However, for temperature in excess of 610 degrees C up to 700 degrees C an almost constant doping efficiency for GaAs is obtained. For GaAs a slight reduction in Si-incorporation efficiency with increasing V/III-ratio is detected. The successful doping characteristics for GaAs have been applied to realize n-GaAs:Si Hall sensor device structures. The lateral homogeneity of the sheet resistance is evaluated as a function of the V/III-ratio and the substrate material. Under optimum conditions the normalized variance of the sheet resistance can be as low as 1%. (C) 1998 Elsevier Science B.V. All rights reserved.