ZnO and N-doped ZnO thin films were grown by MOCVD on sapphire and ZnO substrates. Diethyl zinc and O<sub>2</sub> were used as sources for Zn and O, respectively. A specially designed plasma system was employed to produce atomic N dopant for in-situ doping. Proper disk rotation speeds were found for ZnO growth on different size wafers. High crystal quality N-doped ZnO films were grown based on optimized growth conditions. Wet chemical etch of ZnO was investigated by using NH<sub>4</sub>Cl, and etch activation energy was calculated to be 463meV. Ohmic contact on N-doped ZnO film was achieved by using Ni/Au/Al multiple layers. ZnO based p-n junction has demonstrated rectification. Electroluminescence at about 384nm was obtained from ZnO based LED.
Intentionally doped n-type bulk ZnO has been grown by patented melt technique at Cermet and was used as a substrate for homo-epitaxial growth of p-type ZnO films. The n-type ZnO has a carrier concentration on the order of 10<sup>18</sup>cm<sup>-3</sup> with a mobility of 113cm<sup>2</sup>/Vs, which is good for optical devices. Secondary ion mass spectroscopy (SIMS) profile shows a very uniform distribution of n-type dopant in the ZnO. Excellent transmission from the sharp absorption edge through the visible portion of the spectrum indicates that as grown n-type ZnO is perfect for any optical device applications. P-type ZnO thin films were successfully grown by MOCVD technique on n-type ZnO substrate to form ZnO based p-n junction structure. Cadmium and magnesium doped ZnO films were also grown by MOCVD and resulted in tunable bad gap energy of ZnO based alloy. Ohmic contact layer on n-type ZnO was formed by using Ti/Au and on p-type ZnO was formed by using Ni/Au. The current-voltage (I-V) characteristics of the ZnO based p-n junction exhibited rectification when reverse biased with a breakdown voltage of 10 V and turn-on voltage of 3.3 V. Post anneal of p-type ZnO films showed big improvement on the I-V characteristics. Electroluminescence (EL) spectra obtained from devices driven to 40mA are dominated by a peak at 384nm.