Pd Schottky Contacts on Sol–Gel Derived ZnO Thin Films With Nearly Ideal Richardson Constant

Abstract

This letter reports the temperature-dependent analysis of measured I-V characteristics of Pd/ZnO thin filmbased Schottky diodes grown on n-Si (100) substrates by sol-gel method. Assuming a Gaussian distributed barrier height at the Pd/ZnO interface with a standard deviation (σ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ) around a mean barrier height qφ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B,m</sub> , the analysis estimates the value of Richardson constant ~31.67 Acm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> , which is not only very close to its theoretical value of ~32 Acm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> (for m <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</sub> * = 0.27m <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ), but also the best result reported so far for ZnO-based Schottky contacts. The estimated value of the zero-bias mean barrier height (~1.39 eV) at T = 0 K is also observed to be very close to its theoretical value of 1.42 eV (for work function of Pd = 5.12 eV and electron affinity of ZnO = 3.7 eV).