Lectrical stabilization of CdZnTe by argon plasma treatment and diamond-like carbon passivation

Abstract

The high specific resistance of CdZnTe-based radiation detectors enables high energy resolution and detection sensitivity, as it determines the device's leakage currents. In this work, an ion-plasma surface treatment was developed to enhance the electrical stability and radiation tolerance of CdZnTe crystals. The method integrates Ar ion surface alteration with the following application of a hydrogenated diamond-like carbon ( a -C:H:N) film via PECVD. Argon plasma treatment of CdZnTe eliminates cadmium atoms, creating a near-surface rich-layer of cadmium vacancies (V Cd 2− ). The later application of a diamond-like carbon film guarantees chemical passivation and reinforces the defect structure of the semiconductor material. This in-situ ion-plasma procedure enhances the specific resistance of the CdZnTe structure from 2 × 10 7 to (2-3)×10 8 Ohm cm, decreasing surface leakage currents by roughly one order of magnitude. The enhanced electrical stability is maintained for at least six months, indicating the formation of a stable and irreversible defect configuration during a single technological cycle. After γ-irradiation with a dose of 130 kRad, the values of specific resistance of all studied samples converge to approximately (1-3)×10 9 Ohm cm. This behavior is consistent with radiation-induced self-compensation and Fermi-level pinning near mid-gap. The results show that argon plasma processing and passivation of DLC samples improve the electrical stability and radiation resistance of CdZnTe.This approach is promising for use in high-resolution radiation detectors.