Influence of background concentration induced field on the emission rate signatures of an electron trap in zinc oxide Schottky devices

Abstract

Various well-known research groups have reported points defects in bulk zinc oxide (ZnO) [N-D (intrinsic): 10(14)-10(17) cm(-3)] naming oxygen vacancy, zinc interstitial, and/or zinc antisite having activation energy in the range of 0.32-0.22 eV below conduction band. The attribution is probably based on activation energy of the level which seems not to be plausible in accordance with Vincent et al., [J. Appl. Phys. 50, 5484 (1979)] who suggested that it was necessary to become vigilant before interpreting the data attained for a carrier trap using capacitance transient measurement of diodes having ND greater than 10(15) cm(-3). Accordingly the influence of background free-carrier concentration, ND induced field on the emission rate signatures of an electron point defect in ZnO Schottky devices has been investigated by means of deep level transient spectroscopy. A number of theoretical models were tried to correlate with the experimental data to ascertain the mechanism. Consequently Poole-Frenkel model based on Coulomb potential was found consistent. Based on these investigations the electron trap was attributed to Zn-related charged impurity. Qualitative measurements like current-voltage and capacitance-voltage measurements were also performed to support the results.Original Publication:Hadia Noor, P Klason, Sadia Muniza Faraz, Omer Nour, Qamar Ul Wahab, Magnus Willander and M Asghar, Influence of background concentration induced field on the emission rate signatures of an electron trap in zinc oxide Schottky devices, 2010, JOURNAL OF APPLIED PHYSICS, (107), 10, 103717.http://dx.doi.org/10.1063/1.3428426Copyright: American Institute of Physicshttp://www.aip.org