Investigations of defects in TiO2/HgTe/MoO3 heterostructures and their influence on transport properties

Sreeshma, D and Amardeep, J and Rao, KSRK (2023) Investigations of defects in TiO2/HgTe/MoO3 heterostructures and their influence on transport properties. In: Journal of Physics D: Applied Physics, 56 (35).

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Abstract

The need for simple-to-manufacture, solution-processable, tunable infrared active optoelectronic materials led to the development of infrared colloidal quantum dots, whose band gaps may be easily regulated by dimensional constraints resulting from the quantum confinement. Due to electronic deep-level trap states that limit effective mobility and function as effective recombination centers, nanocrystal (NC)-based optoelectronic devices still perform less well than what is predicted theoretically. The performance of NC-based optoelectronic devices can be considerably improved by identifying and passivating these defect levels. In this study, we use low-temperature I-V, C-V, C-F and the microcontroller-based deep level transient spectroscopy (DLTS) system to investigate the defect levels in the FTO/TiO2/HgTe/MoO3/Au device. The I-V measurements at low temperatures demonstrated the existence of exponential trap states, with an activation energy of 0.24 eV and a trap density of 3.18 × 10 17 cm − 3 . Low-temperature C-V and C-F measurements established the existence of deep trap states. With DLTS, we have located two deep trap levels (traps 1 and 2), with energies of 0.25 and 0.46 eV, capture cross-sections 9.7 × 10 − 23 and 4.35 × 10 − 14 cm 2 and a concentration of 2.4 × 10 17 cm − 3 , respectively. The surface states at the HgTe NCs and the oxygen vacancies at the TiO2 are the leading causes of the trap levels, which are primarily present at the interface of the TiO2/HgTe heterojunction. The transport mechanism in these heterojunction devices was happening mainly through these interface trap states. Passivating these defect levels is vital to increase the device effectiveness.

Item Type:	Journal Article
Publication:	Journal of Physics D: Applied Physics
Publisher:	Institute of Physics
Additional Information:	The copyright for this article belongs to the Institute of Physics.
Keywords:	deep level defects; deep level transient spectroscopy; infrared photovoltaic devices; nanocrystals
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	09 Jul 2023 17:34
Last Modified:	09 Jul 2023 17:34
URI:	https://eprints.iisc.ac.in/id/eprint/82081

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