M. PURICA, E. BUDIANU, E. RUSU, P. ARABADJI
Study of the n-CdS/p-InP Heterojunction for Optoelectronic Device Applications

Abstract.
The n⁺-CdS/p-InP heterojunctions have been prepared by chemical vapor deposition in a quasi-closed volume and H 2 transport of CdS on InP substrate. The n⁺-CdS/p-p⁺-InP heterojunction solar cells obtained using this technique and characterized in AM 1.5 illumination condition have showed a conversion efficiency of 12,6% at I_sc = 16 mA/cm2, U_oc = (0.74–0.78) V. The I-V characteristics of the n-CdS/p-InP heterojunctions in dark condition was studied in the (100–300) K temperature range for charge transport mechanism investigation. It has been established that in the entire temperature range the charge transport mechanism is determined either by charge carrier tunneling or by recombination processes in the charge depleted region. In the direct bias condition and low temperature (T < 150 K) the current is determined by charge carrier indirect tunneling and by generation-recombination and by tunneling processes at 300 K. The current at reverse bias in the temperature range (100–300) K is determined by charge carrier tunneling with local centers participation at low reverse voltage and by interband tunneling at reverse voltage > 1.5 V.