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Activation Characteristics of Implanted Dopants in lnAs,GaSb and GaP After Rapid Thermal Annealing

A. R. Von Neida, K. T. Short, J. M. Brown and S. J. Pearton AT&T Bell Laboratories, Murray Hill, NJ 07974, USA

ABSTRACF We have studied in some detail the activation of implanted Si and Mg ions in InAs,GaSb and 2 GaP after rapid thermal annealing. Even at doses of 1015 cm- , the activation percentage of Mg is relatively high after optimum anneals - 80% in GaP, 55% in GaSb and 45% in InAs. There is considerable outdiffusion of Mg in all three semiconductors for extended heat treatments. The 2 amphoteric species Si shows good activation (60% for 1015 cm- dose) in InAs, a saturation 2 electrically active concentration of -3 x 1013 cm- in GaP, and very low electrical activity in GaSb. The regrowth and damage removal characteristics in the three materials are similar to those of GaAs and InP. INTRODUCTION There is increasing interest in the use of ternary semiconductors in a variety of high speed electronic and photonic circuits. For example, heterojunction bipolar transistors have been demonstrated in the InAlAs-InGaAs systemsl1-21, as well as the formation of 2-dimensional electron 1 gases in InGaAs-InP and InAlAs-InGaAs heterostructures for use in selectively doped transistors3 . Compositionally graded InGaAs layers can also be used to form low resistance non-alloyed ohmic 1 1 contacts to n-type GaAs `6 . InAs is used in a number of multilayer structures with novel transport properties'[7 as are GaP and GaSb. Both of these latter materials have important applications in photonic devices such as lasers and light-emitting diodes. To fully understand the behavior and doping characteristics of these materials in multilayer or ternary semiconductor structures, it is necessary to study them in isolation. In this paper we have investigated the dopant activity and damage recovery processes in InAs, GaSb and GaP substrates implanted with Si or Mg. The redistribution of these dopants during rapid thermal annealing was also studied. Experimental The crystals were all grown by the Czochralski technique either at 3 atmospheres pressure (InAs and GaSb) or at high pressure (45 atm for GaP). The InAs was nominally undoped, and displayed 3 n-type conductivity with a carrier concentration of 5 x 1015 cm- at 77K, with an electron mobility 2 of 6200 cm V-1 sec-'. The GaP was also nominally undoped, with an n-type doping level of 3 2 1.5 x 1016 cm- at 300K. The electron mobility was 4650 cm V-1 sec' at this temperature. Two different GaSb crystals were grown. The first was not doped, and was strongly p-type with a carrier 3 2 concentration of 101s cm- and a hole mobility of 230 cm V-1 sec-' at 300K. This is fairly typical for melt-grown GaSb, and is a result of the presence of a high concentration of stoichiometry related acceptorsftil-l. The second crystal was doped with Te to achieve an n-type doping level of 3 2 2 x 1017 cm- , with an electron mobility of 2900 cm V-1 sec-' at 300 K. After slightly etching the surfaces of wafers from th