Characteristics of Implanted N-Type Profiles in GaAs Annealed in a Controlled Atmosphere

Abstract

A controlled atmosphere technique (CAT) has been developed as an alternative to dielectric encapsulation for the anneal of implanted GaAs. In the CAT, a flowing hydrogen-arsenic atmosphere is adjusted to he near equilibrium with the surface of the implanted GaAs during the heat treatment. The CAT anneal was used to study the characteristics of n-type impurities (Si and S), random implanted at room temperature into GaAs epitaxial layers. In situ implanted silicon distributions were measured before anneal by secondary ion mass spectroscopy and the projected range data show agreement to within 10% with tabulated values for energies 50 to 400 keV. Silicon and sulfur implantations of >2 x 10¹³ cm^-2 annealed at 800 C for 20 min resulted in apparent electrical conversion efficiencies >75%. The CAT annealed profiles are approximately Gaussian near the peaks with exponential tail behavior at lower concentrations.