Steady-state and time-resolved photoconductivity measurements of minority carrier lifetime in ZnTe

Minority carrier lifetime in ZnTe has been determined from steady-state and time-resolved photoconductivity (PC) measurements. Three types of single crystal p-ZnTe (E G = 2.26 eV ) grown by the Bridgman technique were studied : i) as-grown - before and after hydrogen passivation, ii) Zn annealed and iii) In - doped semi-insulating. Steady-state photoconductivity was studied between 80 - 300 K and showed that for as-grown samples, the lifetime went through a sharp maximum of 4.5 x 10 -7 s at 220K, decreasing to 2.5 x 10 -8 s at 300K. For hydrogen passivated samples, the lifetime remained high at 4.5 x 10 -7 s at 300K, due to passivation of deep acceptors O Te . Time-resolved photoconductivity measurements gave values in reasonably good agreement viz. 4.6 x 10 -8 s and 3.2 x 10 -7 s respectively for as-grown and Zn annealed samples. The radiative recombination constant B was thus found to be 1.4 x 10 -9 cm 3 s -1 and 4 x 10 -10 cm 3 s -1 respectively at 300 K for the two samples. PC spectral response studies showed a maximum at 2.41 eV at 300K with slight shift to 2.43 eV occurred on H passivation.