Contacts and ion implantation to 4H silicon carbide

Rectifying and non-rectifying contacts were fabricated in n-type 4H-Silicon Carbide. To improve the characteristics of the fabricated contacts various different surface pre-treatments were used. The impact of these pre-treatments on both contacts types was evaluated, and any improvements recorded. T...

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Main Author: Pope, G.
Published: Swansea University 2004
Subjects:
537
Online Access:http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638549
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spelling ndltd-bl.uk-oai-ethos.bl.uk-6385492015-03-20T05:35:00ZContacts and ion implantation to 4H silicon carbidePope, G.2004Rectifying and non-rectifying contacts were fabricated in n-type 4H-Silicon Carbide. To improve the characteristics of the fabricated contacts various different surface pre-treatments were used. The impact of these pre-treatments on both contacts types was evaluated, and any improvements recorded. The findings report on the improvements made to the specific contact resistance of nickel contacts fabricated to n-type 4H-SiC epilayers. Ohmic contacts with an average value of specific contact resistances as low as 1.15 x 10<sup>-4</sup> Ω cm<sup>2</sup> following annealing at around 900<sup>o</sup>C were created. In addition nickel Ohmic contacts were created with similarly low specific contact resistance, which required no such annealing, a phenomenon never previously reported. Further investigation was conducted into the reasons behind this finding, and a hypothesis developed. Various different surface preparations were also experimented for use in the formation of Schottky contacts. No improvements were seen over the standard cleaning process however. High power Schottky diodes were fabricated using a single nickel Schottky contact that exhibited reverse breakdown voltages of around 600V. This figure was improved upon through the use of boron implantation as an edge termination but at the detriment of the forward I(V) characteristic. Further development of the diodes, using a multiple metal Schottky contact, yielded breakdown voltages of 1kV without the need for any further edge termination. This value is more than 85% of the theoretical value for reverse breakdown. In addition to the work on metal contacts, investigation was also performed into the use of ion implantation for the purpose of semiconductor doping. A database was developed to allow the prediction of implant profiles for both Boron and Nitrogen into SiC. This prediction compared well to experimental results. The damage created by high temperature annealing of SiC and the possible steps to prevent and repair this damage is also investigated.537Swansea University http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638549Electronic Thesis or Dissertation
collection NDLTD
sources NDLTD
topic 537
spellingShingle 537
Pope, G.
Contacts and ion implantation to 4H silicon carbide
description Rectifying and non-rectifying contacts were fabricated in n-type 4H-Silicon Carbide. To improve the characteristics of the fabricated contacts various different surface pre-treatments were used. The impact of these pre-treatments on both contacts types was evaluated, and any improvements recorded. The findings report on the improvements made to the specific contact resistance of nickel contacts fabricated to n-type 4H-SiC epilayers. Ohmic contacts with an average value of specific contact resistances as low as 1.15 x 10<sup>-4</sup> Ω cm<sup>2</sup> following annealing at around 900<sup>o</sup>C were created. In addition nickel Ohmic contacts were created with similarly low specific contact resistance, which required no such annealing, a phenomenon never previously reported. Further investigation was conducted into the reasons behind this finding, and a hypothesis developed. Various different surface preparations were also experimented for use in the formation of Schottky contacts. No improvements were seen over the standard cleaning process however. High power Schottky diodes were fabricated using a single nickel Schottky contact that exhibited reverse breakdown voltages of around 600V. This figure was improved upon through the use of boron implantation as an edge termination but at the detriment of the forward I(V) characteristic. Further development of the diodes, using a multiple metal Schottky contact, yielded breakdown voltages of 1kV without the need for any further edge termination. This value is more than 85% of the theoretical value for reverse breakdown. In addition to the work on metal contacts, investigation was also performed into the use of ion implantation for the purpose of semiconductor doping. A database was developed to allow the prediction of implant profiles for both Boron and Nitrogen into SiC. This prediction compared well to experimental results. The damage created by high temperature annealing of SiC and the possible steps to prevent and repair this damage is also investigated.
author Pope, G.
author_facet Pope, G.
author_sort Pope, G.
title Contacts and ion implantation to 4H silicon carbide
title_short Contacts and ion implantation to 4H silicon carbide
title_full Contacts and ion implantation to 4H silicon carbide
title_fullStr Contacts and ion implantation to 4H silicon carbide
title_full_unstemmed Contacts and ion implantation to 4H silicon carbide
title_sort contacts and ion implantation to 4h silicon carbide
publisher Swansea University
publishDate 2004
url http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638549
work_keys_str_mv AT popeg contactsandionimplantationto4hsiliconcarbide
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