HIGH-EFFICIENCY SILICON DOPING OF INP AND IN0.53GA0.47AS IN GAS-SOURCE AND METALORGANIC MOLECULAR-BEAM EPITAXY USING SILICON TETRABROMIDE

Efficient vapor source Si doping of InP and In0.53Ga0.47As have been demonstrated using SiBr4 as the Si source for both gas source (GSMBE) and metalorganic molecular beam epitaxy (MOMBE). Net electron concentrations ranging from n = 2 X 10(17) to 6.8 X 10(19) cm-3 and from 9 X 10(16) to 3 X 10(19) cm-3 have been obtained for InP and In0.53Ga0.47As, respectively. Comparison of these data with those for Si2H6 indicate that the Si incorporation efficiency with SiBr4 is more than 10 000 times greater than with Si2H6 for substrate temperatures in the range of 475 less-than-or-equal-to T(s) less-than-or-equal-to 500-degrees-C. Specular surface morphologies were obtained, even for the most heavily doped samples. While [Si] as high as 1.8 X 10(20) cm-3 was obtained in InP, the net electron concentrations and 300 K Hall mobilities decrease with increasing [Si] for [Si]>6.8 X 10(19) cm-3. Contact resistances as low as R(c) = 3 X 10(-8) OMEGA cm3 were obtained using a nonalloyed Ti/Pt/Au contact to InP layers doped to n = 6.3 X 10(19) cm-3. During GSMBE growth, an increased Si background concentration ([Si] approximately 2 X 10(17) cm-3) was observed after extended use of the SiBr4 source for these heavy doping concentrations. This increased background was not observed in MOMBE-grown material. Depth profiles of pulse-doped structures indicate the absence of memory effects for structures grown by MOMBE.