Journal of Crystal Growth 285 (2005) 318–326 Effect of hydrogenation on the electrical and optical proper of CdZnTe substrates and HgCdTe epitaxial layers S. Sitharaman , R. Raman, L. Durai, Surendra Pal, Madhukar Gautam, Anjana Nagpal, Shiv Kumar, S.N. Chatterjee, S.C. Gupta Solid State Physics Laboratory (SSPL), Lucknow Road, Timarpur, Delhi 110 054, India Received 20 January 2005; received in revised form 3 August 2005; accepted 29 August 2005 Available online 10 October 2005 Communicated by M.S. Goorsky Abstract In this paper, we report the experimental observations on the effect of plasma hydrogenation in passivating point defects,shallow/deep levels and extended defects in low-resistivity undoped CdZnTe crystals. The optical absorption studies show transmittance improvement in the below gap absorption spectrum. Using variable tem Hall measurement technique, the shallow defect level on which the penetrating hydrogen makes complex, has been identified. In ‘compensated’ n-type HgCdTe epitaxial layers, hydrogenation can improve the resistivity by two magnitude. r 2005 Elsevier B.V. All rights reserved. PACS: 61.72J; 78.55E; 81.65R Keywords: A1. Defects; A1. Hydrogenation; A3. Epitaxy; B2. CdZnTe; B2. HgCdTe 1. Introduction Recently,passivationof point defects,line defectsand impuritiesby hydrogenationhas assumed great significance in III–V and II–VI compound semiconductors [1,2]. Apart from this, attemptsare being made in II–VI compound semiconductors wherecontrolled hydrogenation can effectively beutilised forthe p–n junction formation by monitoring the point defects namely vacancies and interstitials [3]. Undoped cadmium zinc telluride (CZT) substrates with low-resistivity values around 10 3 O cm are used for the epitaxial growth of mercury cadmium telluride (MCT). The crystalgrowershave theoretically modelled this low-resistivity phenomenon by taking into account shallow defectcompensation [4]. The ultimate electrical properties of the grown MCT epitaxial ARTICLE IN PRESS www.elsevier.com/locate/jcrysgro 0022-0248/$ - see front matter r 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.jcrysgro.2005.08.038 Corresponding author. Tel.: 9101123972093; fax: 91 11 23984285. E-mail address: sitharaman/sspl@ssplnet.org (S. Sitharaman).