We describe the fabrication of ultrahigh-density beta-Ga2O3 Schottky and N-doped beta-Ga2O3/beta-Ga2O3 p-n nanowire junctions via microwave plasma enhanced chemical vapor deposition and thermal chemical vapor deposition. The electron transport mechanisms with Schottky and p-n nanowire junctions were characterized by current-voltage (I-V-sd) measurements. The I-V-sd curve of different amount of the nanowires is greatly influenced by the potential barriers on the gap of Schottky nanowire junctions. N-2 plasma treatment led to rectifying electrical characteristics, suggesting that near surface was compensated by ion-induced deep-level states, which can be verified by cathodoluminescence spectrum. The current transport through p-n nanowire junctions is dominated by the deep-level-assisted tunneling mechanism for -0.8 V < V-sd < 0.6 V and by the space-charge limited conductive mechanism beyond 0.6 V. The detailed I-V-sd characteristics of the p-n nanowire junctions have been investigated in the temperature range 323-373 K. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3530787] All rights reserved.