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Title: Impact of surface morphology of Si substrate on performance of Si/ZnO heterojunction devices grown by atomic layer deposition technique

Abstract

In this paper, the authors have investigated the structural, optical, and electrical characteristics of silicon nanowire (SiNW)/zinc oxide (ZnO) core–shell nanostructure heterojunctions and compared their characteristics with Si/ZnO planar heterojunctions to investigate the effect of surface morphology of Si substrate in the characteristics of Si/ZnO heterojunction devices. In this work, ZnO thin film was conformally deposited on both p-type 〈100〉 planar Si substrate and substrate with vertically aligned SiNW arrays by atomic layer deposition (ALD) method. The x-ray diffraction spectra show that the crystalline structures of Si/ZnO heterojunctions are having (101) preferred orientation, whereas vertically oriented SiNW/ZnO core–shell heterojunctions are having (002)-oriented wurtzite crystalline structures. The photoluminescence (PL) spectra of Si/ZnO heterojunctions show a very sharp single peak at 377 nm, corresponding to the bandgap of ZnO material with no other defect peaks in visible region; hence, these devices can have applications only in UV region. On the other hand, SiNW/ZnO heterojunctions are having band-edge peak at 378 nm along with a broad emission band, spreading almost throughout the entire visible region with a peak around 550 nm. Therefore, ALD-grown SiNW/ZnO heterojunctions can emit green and red light simultaneously. Reflectivity measurement of the heterojunctions further confirms the enhancement of visible region peak inmore » the PL spectra of SiNW/ZnO heterojunctions, as the surface of the SiNW/ZnO heterojunctions exhibits extremely low reflectance (<3%) in the visible wavelength region compared to Si/ZnO heterojunctions (>20%). The current–voltage characteristics of both Si/ZnO and SiNW/ZnO heterojunctions are measured with large area ohmic contacts on top and bottom of the structure to compare the electrical characteristics of the devices. Due to large surface to-volume ratio of SiNW/ZnO core–shell heterojunction devices, the output current rating is about 130 times larger compared to their planar version at 2 V forward bias voltage. This higher output current rating can be exploited for fabricating high-performance nanoelectronic and optoelectronic devices in near future.« less

Authors:
;  [1];  [2]
  1. Department of Electronics and Communication Engineering, Motilal Neheru National Institute of Technology, Allahabad 211004 (India)
  2. Department of Electronics Engineering, Indian Institute of Technology (BHU), Varanasi 221005 (India)
Publication Date:
OSTI Identifier:
22318084
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films; Journal Volume: 33; Journal Issue: 1; Other Information: (c) 2014 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; DEPOSITION; HETEROJUNCTIONS; NANOSTRUCTURES; PERFORMANCE; PHOTOLUMINESCENCE; SUBSTRATES; SURFACES; X-RAY DIFFRACTION; ZINC OXIDES

Citation Formats

Hazra, Purnima, Singh, Satyendra Kumar, and Jit, Satyabrata, E-mail: sjit.ece@itbhu.ac.in. Impact of surface morphology of Si substrate on performance of Si/ZnO heterojunction devices grown by atomic layer deposition technique. United States: N. p., 2015. Web. doi:10.1116/1.4900719.
Hazra, Purnima, Singh, Satyendra Kumar, & Jit, Satyabrata, E-mail: sjit.ece@itbhu.ac.in. Impact of surface morphology of Si substrate on performance of Si/ZnO heterojunction devices grown by atomic layer deposition technique. United States. doi:10.1116/1.4900719.
Hazra, Purnima, Singh, Satyendra Kumar, and Jit, Satyabrata, E-mail: sjit.ece@itbhu.ac.in. Thu . "Impact of surface morphology of Si substrate on performance of Si/ZnO heterojunction devices grown by atomic layer deposition technique". United States. doi:10.1116/1.4900719.
@article{osti_22318084,
title = {Impact of surface morphology of Si substrate on performance of Si/ZnO heterojunction devices grown by atomic layer deposition technique},
author = {Hazra, Purnima and Singh, Satyendra Kumar and Jit, Satyabrata, E-mail: sjit.ece@itbhu.ac.in},
abstractNote = {In this paper, the authors have investigated the structural, optical, and electrical characteristics of silicon nanowire (SiNW)/zinc oxide (ZnO) core–shell nanostructure heterojunctions and compared their characteristics with Si/ZnO planar heterojunctions to investigate the effect of surface morphology of Si substrate in the characteristics of Si/ZnO heterojunction devices. In this work, ZnO thin film was conformally deposited on both p-type 〈100〉 planar Si substrate and substrate with vertically aligned SiNW arrays by atomic layer deposition (ALD) method. The x-ray diffraction spectra show that the crystalline structures of Si/ZnO heterojunctions are having (101) preferred orientation, whereas vertically oriented SiNW/ZnO core–shell heterojunctions are having (002)-oriented wurtzite crystalline structures. The photoluminescence (PL) spectra of Si/ZnO heterojunctions show a very sharp single peak at 377 nm, corresponding to the bandgap of ZnO material with no other defect peaks in visible region; hence, these devices can have applications only in UV region. On the other hand, SiNW/ZnO heterojunctions are having band-edge peak at 378 nm along with a broad emission band, spreading almost throughout the entire visible region with a peak around 550 nm. Therefore, ALD-grown SiNW/ZnO heterojunctions can emit green and red light simultaneously. Reflectivity measurement of the heterojunctions further confirms the enhancement of visible region peak in the PL spectra of SiNW/ZnO heterojunctions, as the surface of the SiNW/ZnO heterojunctions exhibits extremely low reflectance (<3%) in the visible wavelength region compared to Si/ZnO heterojunctions (>20%). The current–voltage characteristics of both Si/ZnO and SiNW/ZnO heterojunctions are measured with large area ohmic contacts on top and bottom of the structure to compare the electrical characteristics of the devices. Due to large surface to-volume ratio of SiNW/ZnO core–shell heterojunction devices, the output current rating is about 130 times larger compared to their planar version at 2 V forward bias voltage. This higher output current rating can be exploited for fabricating high-performance nanoelectronic and optoelectronic devices in near future.},
doi = {10.1116/1.4900719},
journal = {Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films},
number = 1,
volume = 33,
place = {United States},
year = {Thu Jan 01 00:00:00 EST 2015},
month = {Thu Jan 01 00:00:00 EST 2015}
}