The influence of stoichiometry on the growth of tellurium-doped indium antimonide for magnetic field sensors

Indium antimonide magnetoresistors are used as magnetic position sensors in very demanding automotive environments such as crankshaft and camshaft sensors for engine control. The use of tellurium as an n-type dopant was studied using Hall effect measurements up to 200 degrees C, Hall depth profiling, and secondary ion mass spectroscopy. The films were grown by metal organic chemical vapor deposition using trimethyl indium, trisdimethylamino antimony, and diethyl telluride. It was found that the incorporation of tellurium strongly depends upon the V/III ratio during growth, implying that it is influenced by the availability of antimony vacancies. Thus, our results show that the reproducibility of tellurium doping is not limited by memory effects in a well-designed reactor, but by the control of stoichiometry. It is now possible to grow films with optimum doping profile and with good uniformity and reproducibility over hundreds of growth runs. These films can be used to make magnetoresistors that have good sensitivity to a magnetic field and good stability over a wide temperature range. (C) 1998 Elsevier Science B.V. All rights reserved.