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

Minority carrier lifetime in ZnTe has been determined fi om 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 accepters 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.