Dopant incorporation behaviour during MOMBE growth of InP on (1 0 0), {1 1 1} and nonplanar surfaces

The doping of InP using Si and Zn has been studied for MOMBE growth on (1 0 0), (1 1 1)A, (1 1 1)B and for the overgrowth of nonplanar surfaces. The investigation of large area growth shows that Si acts as a donor on the three investigated surfaces. The free electron concentrations are always highest on (1 1 1)B and lowest on(1 1 1)A. Zn doping yields free hole concentrations which are highest on (1 1 1)A and lowest on (1 1 1)B. Consequently, co-doping using Si together with Zn yields a net n-type carrier concentration on(1 0 0) and(1 1 1)B surfaces, whereas a net p-type behaviour is found on (1 1 1)A surfaces within the same growth run. These results obtained from large:area growth can be transferred to the overgrowth of localized (1 0 0)/(1 1 1)A steps on nonplanar substrates; using Si as dopant the free electron concentration on the(1 1 1)A facet decreases by a factor two compared with the (1 0 0) surface. Si-Zn co-doping leads to a drop in carrier concentration of at least one order of magnitude. Comparison with large area growth suggests that a lateral (pn)-junction can be realized within a single growth step. (C) 1998 Elsevier Science B.V. All rights reserved.