Surface induced negative photoconductivity in p-type ZnSe:Bi nanowires and their nano-optoelectronic applications

Single-crystal p-type ZnSe nanowires (NWs) with zinc blende structure and [21-1] growth direction were synthesized by using bismuth (Bi) as dopant via a thermal co-evaporation method. The ZnSe : Bi NWs showed evident p-type conductivity with hole concentration up to 4.1 x 10(18) cm(-3) after the acceptor activation. Negative photoconductivity was first investigated in the p-ZnSe NWs, i.e., the conductivity of the NWs under light was dramatically lower than that in the dark. Surface effects arising from oxygen absorption and photo-desorption were suggested to be responsible for this. By using Al as the Schottky gate, high-performance nano-metal-semiconductor field-effect transistors (nanoMESFETs) were constructed, and measurements on the Al/p-ZnSe NW Schottky diode also revealed the bias-dependent photoresponse. It is expected that the p-type ZnSe : Bi NWs will have great potential in nano-optoelectronic applications.