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

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 , [ 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 N D greater than 10 15 cm − 3 . Accordingly the influence of background free-carrier concentration, N D 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.