Electrochemical capacitance voltage profiling of the narrow band gap semiconductor InAs

InAs is a narrow band gap compound semiconductor with potential application s in infra-red detectors and high speed transistors. In order to facilitate device design using this material, it is essential that carrier concentrat ion profiles be accurately known. Capacitance-voltage (CV) profiling is oft en employed for this purpose. Due to surface Fermi level pinning, it is dif ficult to form metal Schottky contacts to InAs layers, making conventional CV profiling difficult. Electrochemical CV (ECV) measurements have been suc cessfully performed on InAs epilayers grown by molecular beam epitaxy on Ga P. A solution of 0.2 M EDTA with 0.2M NaOH and 10-20% by volume of ethylene diamine acts both as an etchant and as a Schottky contact to InAs. The prof iles obtained for undoped InAs layers were compared to Hall effect data, an d showed good agreement. ECV profiling of thick layers with p- and n-type d oped regions is also demonstrated.