CHARACTERIZATION OF ANNEALED HIGH-RESISTIVITY INP GROWN BY HE-PLASMA-ASSISTED EPITAXY

In this work we report on the effect of annealing high-resistivity InP grown by gas source molecular beam epitaxy in the presence of an elec tron cyclotron resonance generated He plasma, Previous work has shown that InP grown using this technique exhibits resistivity greater than 10(5) Ohm cm and Be-doped InGaAsP (lattice matched to InP, band-gap wa velength 1.5 mu m) exhibits subpicosecond carrier lifetime. This behav ior is due to the presence of defects caused by the plasma particles d uring growth. To gain a better understanding of the nature of these de fects, samples were annealed over the temperature range 500-700 degree s C and evaluated by variable energy positron annihilation measurement s, transient ellipsometric surface photoreflectance, sheet resistance, and n-i-n device resistivity studies. For all samples. the resistivit y increased with annealing, as did the carrier lifetime from the optic al measurements which suggests the presence of more than one defect ty pe in the material. Positron annihilation studies suggest that the ope n volume defects, present in the as-grown material as single vacancies and vacancy clusters, become larger upon annealing although this effe ct may be obscured in the Be-doped samples at higher annealing tempera tures. The Be-doped samples were found to be mon resistive and optical ly faster than the undoped material, Also, the sheet resistance measur ements may indicate that the Be in the doped samples is activated at a nnealing temperatures above 600 degrees C, since the material changes from weakly n-type to p-type. (C) 1995 American Vacuum Society. [S0734 -2101(98)04002-0].