Current leakage mechanisms related to threading dislocations in Ge-rich SiGe heterostructures grown on Si(001)

Tetzner, H., Fischer, I.A., Skibitzki, O., Mirza, M. M.A. , Manganelli, C.L., Luongo, G., Spirito, D., Paul, D. J. , De Seta, M. and Capellini, G. (2021) Current leakage mechanisms related to threading dislocations in Ge-rich SiGe heterostructures grown on Si(001). Applied Physics Letters, 119(15), 153504. (doi: 10.1063/5.0064477)

Abstract

This work investigates the role of threading dislocation densities (TDD) in the low density regime on the vertical transport in Si0.06Ge0.94 heterostructures integrated on Si(001). The use of unintentionally doped Si0.06Ge0.94 layers enables the study of the impact of grown-in threading dislocations (TD) without interaction with processing-induced defects originating, e.g., from dopant implantation. The studied heterolayers, while equal in composition, the degree of strain relaxation, and the thickness feature three different values for the TDD as 3 × 106, 9 × 106, and 2 × 107 cm−2. Current–voltage measurements reveal that leakage currents do not scale linearly with TDD. The temperature dependence of the leakage currents suggests a strong contribution of field-enhanced carrier generation to the current transport with the trap-assisted tunneling via TD-induced defect states identified as the dominant transport mechanism at room temperature. At lower temperatures and at high electric fields, direct band-to-band tunneling without direct interactions with defect levels becomes the dominating type of transport. Leakage currents related to emission from mid-gap traps by the Shockley–Read–Hall (SRH) generation are observed at higher temperatures (>100 °C). Here, we see a reduced contribution coming from SRH in our material, featuring the minimal TDD (3 × 106 cm−2), which we attribute to a reduction in point defect clusters trapped in the TD strain fields.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Paul, Professor Douglas and Mirza, Dr Muhammad M A
• Authors: Tetzner, H., Fischer, I.A., Skibitzki, O., Mirza, M. M.A., Manganelli, C.L., Luongo, G., Spirito, D., Paul, D. J., De Seta, M., and Capellini, G.
• College/School: College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
• Journal Name: Applied Physics Letters
• Publisher: AIP Publishing
• ISSN: 0003-6951
• ISSN (Online): 1077-3118
• Published Online: 12 October 2021
• Copyright Holders: Copyright © 2021 The Authors
• First Published: First published in Applied Physics Letters 119(15):153504
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher

Project Code	Award No	Project Name	Principal Investigator	Funder's Name	Funder Ref	Lead Dept
301516		Far-infrared Lasers Assembled using Silicon	Douglas Paul	European Commission (EC)	766719	ENG - Electronics & Nanoscale Engineering