Modelling and characterization of electrical properties of ZnO-based heterostructure for solar cell applications

Abstract

Zinc oxide (ZnO) is becoming an attractive semiconductor material within optoelectronics and solar cell applications. The usage of ZnO as a transparent conducting oxide (TCO) is interesting both as electrode in Si-based cells and used in band gap engineered heterojunction solar cells. Device performance can be estimated by charge carrier simulation using commercially available software (TCAD), but a reliable model of the transport properties of ZnO is needed.

In the present study, ZnO-based heterostructure and Schottky contact have been modelled and simulated for their electrical characteristics. The ZnO model was developed and investigated through experimental characterization of Pd Schottky contacts on ZnO using capacitance-voltage (CV), current-voltage (IV), deep level transient spectroscopy (DLTS) and admittance spectroscopy (ADSPEC).

A heterostructure of highly doped n-type ZnO on Si was explored for its potential within solar cell application. In the ideal model, an illumination using single wavelength of 2eV and a power of 2.9mW/cm^2 corresponding to AM1.5 was implemented and the highest achieved conversion efficiency was 15.9% on p-type Si substrate.