Stable p-type ZnO:P nanowire/n-type ZnO:Ga film junctions, reproducibly grown by two-step pulsed laser deposition

Abstract

ZnO p-n junctions were grown by two-step pulsed laser deposition (PLD) on a-plane sapphire substrates using a Ga-doped ZnO thin film as n-type conducting material. On top of these n-type films, phosphorous-doped ZnO (ZnO:P) nanowires were prepared by high-pressure PLD. Rectifying I-V curves with threshold voltage of about 3.2 V and a forward/reverse current ratio of 100 at ±3.5 V were measured reproducibly on these junctions. There are three independent indications for reproducible and about 1 year stable p-type conductivity of the ZnO:P wires: (1) Low-temperature cathodoluminescence of single ZnO:P nanowires exhibits phosphorus acceptor-related peaks: (A0,X), (e,A0), and donor-acceptor pair [B. Q. Cao et al., Nanotechnology 18, 455707 (2007)], (2) bottom-gate field effect transistors using undoped (n-type) ZnO and ZnO:P wires showed opposite transfer characteristics [B. Q. Cao et al., Phys. Status Solidi (RRL) 2, 37 (2008)], and (3) the rectifying I-V characteristics of the ZnO:P nanowire/ZnO:Ga-film junctions as shown here.