High-efficiency silicon doping of InP and In0.53Ga0.47As in gas source and metalorganic molecular beam epitaxy using silicon tetrabromide

Abstract

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=2×1017 to 6.8×1019 cm−3 and from 9×1016 to 3×1019 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≤Ts≤500 °C. Specular surface morphologies were obtained, even for the most heavily doped samples. While [Si] as high as 1.8×1020 cm−3 was obtained in InP, the net electron concentrations and 300 K Hall mobilities decrease with increasing [Si] for [Si]≳6.8×1019 cm−3. Contact resistances as low as Rc=3×10−8 Ω cm2 were obtained using a nonalloyed Ti/Pt/Au contact to InP layers doped to n=6.3×1019 cm−3. During GSMBE growth, an increased Si background concentration ([Si]∼2×1017 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.