Presentation Details
| A Minority-Carrier Trap State Detected in CdSeTe:As using Deep Level Transient Spectroscopy Steve Johnston, Hongling Lott, Eric Colegrove, Joel N.Duenow, Joshua A.Brown, Andrea T.Mathew, B.Edward Sartor, Robert Morrissey, Matthew O.Reese. National Laboratory of the Rockies, Golden, CO, USA |
Abstract
Arsenic-doped CdSeTe photovoltaic devices are fabricated using facilities at the National Laboratory of the Rockies. Thermally evaporated CdSeTe is first deposited on transparent conductive oxide coated soda-lime glass. Then, CdTe:As is deposited using either vapor transport deposition (VTD) or molecular beam epitaxy (MBE). The devices are completed using a CdCl2 treatment and back contact metallization. Samples are conditioned prior to measurement with either light soaking or applied forward bias current. An electron trap level is detected in these samples when measuring with deep level transient spectroscopy (DLTS). The defect level’s activation energy is around 0.4 eV for the VTD samples and 0.3 eV for the MBE samples. Trap densities, NT, are near 1015 cm-3 for the VTD samples and 1014 cm-3 for the MBE samples, with both having NA ~1016 cm-3. DLTS is also measured after samples have transitioned to a dark state. The dominant electron trap DLTS signal shows peaks shifting to higher temperature and effectively increasing the trap activation energy to ~0.5 eV. The gradually increasing activation energies during the light to dark transitions suggest a potential barrier at the front interface that changes with the light and dark conditions.
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No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author.
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