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Title: Defects and electrical behavior in 1 MeV Si{sup +}-ion-irradiated 4H-SiC Schottky diodes

Abstract

In this paper, the formation and evolution of defects induced by ion irradiation with 1 MeV Si{sup +} ions in Ni{sub 2}Si/4H-SiC Schottky diodes were studied and correlated with the electrical properties of the contacts. The current-voltage characteristics of the contacts monitored before and after irradiation showed an increase of the Schottky barrier height, of the series resistance, and of the leakage current with increasing irradiation fluence. The changes in the barrier height and in the series resistance values could be attributed to the dopant deactivation in the near-interface region, while the increase of the leakage current was associated with the formation of irradiation-induced defects. These defects showed an evolution with increasing irradiation fluence. Moreover, a combination of deep-level transient spectroscopy and current-voltage measurements of the diodes allowed us to demonstrate that the Z{sub 1}/Z{sub 2} center of 4H-SiC has the major influence on the increase of the diodes leakage current in the irradiated material.

Authors:
; ; ; ; ;  [1];  [2]
  1. CNR-IMM, Sezione di Catania, Stradale Primosole 50, I-95121 Catania (Italy)
  2. (Italy)
Publication Date:
OSTI Identifier:
20787785
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 99; Journal Issue: 1; Other Information: DOI: 10.1063/1.2158501; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; DEACTIVATION; DEEP LEVEL TRANSIENT SPECTROSCOPY; ELECTRIC CONDUCTIVITY; ELECTRIC POTENTIAL; INTERFACES; ION BEAMS; IRRADIATION; LEAKAGE CURRENT; MEV RANGE 01-10; SCHOTTKY BARRIER DIODES; SCHOTTKY DEFECTS; SEMICONDUCTOR MATERIALS; SILICON CARBIDES; SILICON IONS

Citation Formats

Roccaforte, F., Libertino, S., Raineri, V., Ruggiero, A., Massimino, V., Calcagno, L., and Dipartimento di Fisica e Astronomia, Universita di Catania, via S. Sofia 64, I-95123 Catania. Defects and electrical behavior in 1 MeV Si{sup +}-ion-irradiated 4H-SiC Schottky diodes. United States: N. p., 2006. Web. doi:10.1063/1.2158501.
Roccaforte, F., Libertino, S., Raineri, V., Ruggiero, A., Massimino, V., Calcagno, L., & Dipartimento di Fisica e Astronomia, Universita di Catania, via S. Sofia 64, I-95123 Catania. Defects and electrical behavior in 1 MeV Si{sup +}-ion-irradiated 4H-SiC Schottky diodes. United States. doi:10.1063/1.2158501.
Roccaforte, F., Libertino, S., Raineri, V., Ruggiero, A., Massimino, V., Calcagno, L., and Dipartimento di Fisica e Astronomia, Universita di Catania, via S. Sofia 64, I-95123 Catania. Sun . "Defects and electrical behavior in 1 MeV Si{sup +}-ion-irradiated 4H-SiC Schottky diodes". United States. doi:10.1063/1.2158501.
@article{osti_20787785,
title = {Defects and electrical behavior in 1 MeV Si{sup +}-ion-irradiated 4H-SiC Schottky diodes},
author = {Roccaforte, F. and Libertino, S. and Raineri, V. and Ruggiero, A. and Massimino, V. and Calcagno, L. and Dipartimento di Fisica e Astronomia, Universita di Catania, via S. Sofia 64, I-95123 Catania},
abstractNote = {In this paper, the formation and evolution of defects induced by ion irradiation with 1 MeV Si{sup +} ions in Ni{sub 2}Si/4H-SiC Schottky diodes were studied and correlated with the electrical properties of the contacts. The current-voltage characteristics of the contacts monitored before and after irradiation showed an increase of the Schottky barrier height, of the series resistance, and of the leakage current with increasing irradiation fluence. The changes in the barrier height and in the series resistance values could be attributed to the dopant deactivation in the near-interface region, while the increase of the leakage current was associated with the formation of irradiation-induced defects. These defects showed an evolution with increasing irradiation fluence. Moreover, a combination of deep-level transient spectroscopy and current-voltage measurements of the diodes allowed us to demonstrate that the Z{sub 1}/Z{sub 2} center of 4H-SiC has the major influence on the increase of the diodes leakage current in the irradiated material.},
doi = {10.1063/1.2158501},
journal = {Journal of Applied Physics},
number = 1,
volume = 99,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • Defects in SiC degrade the electrical properties and yield of devices made from this material. This article examines morphological defects in 4H-SiC and defects visible in electron beam-induced current (EBIC) images and their effects on the electrical characteristics of Schottky diodes. Optical Nomarski microscopy and atomic force microscopy were used to observe the morphological defects, which are classified into 26 types based on appearance alone. Forward and reverse current-voltage characteristics were used to extract barrier heights, ideality factors, and breakdown voltages. Barrier heights decrease about linearly with increasing ideality factor, which is explained by discrete patches of low barrier heightmore » within the main contact. Barrier height, ideality, and breakdown voltage all degrade with increasing device diameter, suggesting that discrete defects are responsible. Electroluminescence was observed under reverse bias from microplasmas associated with defects containing micropipes. EBIC measurements reveal several types of features corresponding to recombination centers. The density of dark spots observed by EBIC correlates strongly with ideality factor and barrier height. Most morphological defects do not affect the reverse characteristics when no micropipes are present, but lower the barrier height and worsen the ideality factor. However, certain multiple-tailed defects, irregularly shaped defects and triangular defects with 3C inclusions substantially degrade both breakdown voltage and barrier height, and account for most of the bad devices that do not contain micropipes. Micropipes in these wafers are also frequently found to be of Type II, which do not run parallel to the c axis.« less
  • Defects in SiC degrade the electrical properties and yield of devices made from this material. This article examines morphological defects in 4H-SiC and defects visible in electron beam-induced current (EBIC) images and their effects on the electrical characteristics of Schottky diodes. Optical Nomarski microscopy and atomic force microscopy were used to observe the morphological defects, which are classified into 26 types based on appearance alone. Forward and reverse current-voltage characteristics were used to extract barrier heights, ideality factors, and breakdown voltages. Barrier heights decrease about linearly with increasing ideality factor, which is explained by discrete patches of low barrier heightmore » within the main contact. Barrier height, ideality, and breakdown voltage all degrade with increasing device diameter, suggesting that discrete defects are responsible. Electroluminescence was observed under reverse bias from microplasmas associated with defects containing micropipes. EBIC measurements reveal several types of features corresponding to recombination centers. The density of dark spots observed by EBIC correlates strongly with ideality factor and barrier height. Most morphological defects do not affect the reverse characteristics when no micropipes are present, but lower the barrier height and worsen the ideality factor. However, certain multiple-tailed defects, irregularly shaped defects and triangular defects with 3C inclusions substantially degrade both breakdown voltage and barrier height, and account for most of the bad devices that do not contain micropipes. Micropipes in these wafers are also frequently found to be of Type II, which do not run parallel to the c axis.« less
  • Spectroscopic performance of Schottky barrier alpha particle detectors fabricated on 50 μm thick n-type 4H-SiC epitaxial layers containing Z{sub 1/2}, EH{sub 5}, and Ci1 deep levels were investigated. The device performance was evaluated on the basis of junction current/capacitance characterization and alpha pulse-height spectroscopy. Capacitance mode deep level transient spectroscopy revealed the presence of the above-mentioned deep levels along with two shallow level defects related to titanium impurities (Ti(h) and Ti(c)) and an unidentified deep electron trap located at 2.4 eV below the conduction band minimum, which is being reported for the first time. The concentration of the lifetime killer Z{sub 1/2}more » defects was found to be 1.7 × 10{sup 13} cm{sup −3}. The charge transport and collection efficiency results obtained from the alpha particle pulse-height spectroscopy were interpreted using a drift-diffusion charge transport model. Based on these investigations, the physics behind the correlation of the detector properties viz., energy resolution and charge collection efficiency, the junction properties like uniformity in barrier-height, leakage current, and effective doping concentration, and the presence of defects has been discussed in details. The studies also revealed that the dominating contribution to the charge collection efficiency was due to the diffusion of charge carriers generated in the neutral region of the detector. The 10 mm{sup 2} large area detectors demonstrated an impressive energy resolution of 1.8% for 5486 keV alpha particles at an optimized operating reverse bias of 130 V.« less
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  • Pulsed reverse current-voltage characteristics have been measured in the breakdown region for 1-kV 4H-SiC Schottky diodes terminated with a boron-implanted p-n junction. It was shown that the dynamic breakdown voltage of the diodes increases as the pulses become shorter. Owing to the homogeneous avalanche formation at the edge of the guard p-n junction and to the high differential resistance in the breakdown region, the diodes sustain without degradation a pulsed reverse voltage substantially exceeding the static breakdown threshold. Characteristic features of the pulsed breakdown are considered in relation to the specific properties of the boron-implanted guard p-n junction.