Lead telluride and its highhyphen;energy gap alloys are useful for long wavelength diode lasers. In the present study, the control of a donor (Bi) and of an acceptor (Tl) impurity in PbTe was studied in PbTe grown by molecularhyphen;beam epitaxy. Several analytical techniques were used, including scanning Auger electron spectroscopy, secondary ion mass spectroscopy, conventional carrier transport measurements, and surface probe thermoelectric measurements. It was observed that bismuth incorporates well and undergoes negligible diffusion over the range of growth conditions used. Thallium surface segregates at high concentrations and diffuses appreciably at high growth temperatures and at high concentrations. Thus, it is only suitable for use in highly dimensionally defined structures at moderate to low concentrations and at relatively low growth temperatures.
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