Postgrowth Annealing of MOVPE-Grown Single-Crystal CdTe Epilayers on (211) Si Substrates

Effects of cyclic rapid thermal annealing of metalorganic vapor-phase epitaxy grown single-crystal CdTe layers on (211) Si substrates are investigated. Typically, 5-mu m-thick CdTe layers were grown directly on the Si substrates after some substrate pretreatments but without growing other intermediate layers, and annealed ex-situ in a flowing hydrogen atmosphere. We varied the annealing temperature from 500 degrees C to 1000 degrees C, annealing times from 30 to 90 s, and the number of annealing cycles from 1 to 9. Improvement in the crystal quality was confirmed by the full-width at half-maximum values of double-crystal rocking curves for the annealing temperatures between 800 degrees C and 900 degrees C. Furthermore, the 4.2-K photoluminescence measurement and the current-voltage measurements revealed that the conductivity type and the resistivity of the crystals do not change after annealing.