Regulation of Te oxide layer on a CdZnTe film for adjusting surface contact of a CdZnTe-based device

The control of the interface states between the electric contacts and semiconductor is a key issue to develop high-performance functional devices. The polishing, passivation, and oxidation processes can optimize the surface states of the CdZnTe (CZT) film to improve the contact characteristics with the electrode and tailor the resistivity to control the electrical performance. In this work, a serial of surface treatments including mechanical polishing (MP) + chemical polishing (CP) + surface passivation (SP) were conducted to improve the surface states of the CZT film. A transparent Ga-doped Zinc oxide (GZO) was used as the electrode to fabricate the metal-semiconductor-metal (MSM) CZT-based device. The surface treatments of MP, CP, and SP greatly improved the surface contact between CZT films and GZO electrodes. By controlling the thickness of Te oxide layers on CZT film surfaces through the atmospheric oxidation (AO) and the no-atmospheric oxidation (NAO), the thicknesses of oxide layers on CZT film surfaces were adjusted. The X-ray photoelectron spectroscopy (XPS) was used to observe the oxidation sate of the Te oxide layer. The thickness of the Te oxide layer of CZT film surface in atmosphere environment was evaluated as 18–∼20 nm through the in-situ XPS measurement, while that of the CZT film in insolated atmosphere was 5∼7 nm. In contrast, the CZT film-based device under the combination treatments of MP + CP + SP + AO exhibit a surface roughness of ∼4 nm, leading to a significant reduction in the leakage current. The present work provides a strategy to control the thickness of Te oxide layer on the CZT film surface and fabricate a device with a lower current.