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Title: A View from the Past: The Development of Wide-Bandgap Semiconductors

  1. Keystone, contractor to National Security Technologies, LLC, Special Technologies Laboratory
Publication Date:
Research Org.:
Nevada Test Site/National Security Technologies, LLC (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
Report Number(s):
DOE Contract Number:
Resource Type:
Resource Relation:
Conference: The presentation is updated and given once or twice a year, in support of the Site-Directed Research and Development Program.
Country of Publication:
United States
36 MATERIALS SCIENCE; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 74 ATOMIC AND MOLECULAR PHYSICS; gamma spectroscopy, semiconductors, resistivity, mercuric iodide, polarization, Frisch grid

Citation Formats

Franks, Larry. A View from the Past: The Development of Wide-Bandgap Semiconductors. United States: N. p., 2017. Web.
Franks, Larry. A View from the Past: The Development of Wide-Bandgap Semiconductors. United States.
Franks, Larry. Fri . "A View from the Past: The Development of Wide-Bandgap Semiconductors". United States. doi:.
title = {A View from the Past: The Development of Wide-Bandgap Semiconductors},
author = {Franks, Larry},
abstractNote = {},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Mar 31 00:00:00 EDT 2017},
month = {Fri Mar 31 00:00:00 EDT 2017}

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  • The exact definition of wide bandgap semiconductors versus conventional semiconductors is rather ambiguous. A variety of different semiconductors have been discussed in the present symposium, but the major emphasis, of course dictated by the participant response, has been placed on diamond and silicon carbide. Simply stated, diamond as an emerging material has the greater potential for many of these applications; however, silicon carbide is in a much more advanced stage of development. With the high level of activity in diamond research and development, it may be expected that many of the technological hurdles facing this material will be overcome inmore » the years ahead. On the other hand, if certain key problems cannot be resolved (i.e., a shallow n-type dopant and a heteroepitaxial substrate), or if economic considerations are not favorable, then silicon carbide may be the wide bandgap semiconductor of choice for many of the aforementioned applications. Furthermore, other materials (some discussed in this symposium) will continue to be developed and compete for niches in this fast paced, rapidly growing market.« less
  • The wide gap materials SiC, GaN and to a lesser extent diamond are attracting great interest for high power/high temperature electronics. There are a host of device processing challenges presented by these materials because of their physical and chemical stability, including difficulty in achieving stable, low contact resistances, especially for one conductivity type, absence of convenient wet etch recipes, generally slow dry etch rates, the high temperatures needed for implant activation, control of suitable gate dielectrics and the lack of cheap, large diameter conducting and semi-insulating substrates. The relatively deep ionization levels of some of the common dopants (Mg, inmore » GaN; B, Al in SiC; P in diamond) means that carrier densities may be low at room temperature even if the impurity is electrically active - this problem will be reduced at elevated temperature, and thus contact resistances will be greatly improved provided the metallization is stable and reliable. Some recent work with CoSi{sub x} on SiC and W-alloys on GaN show promise for improved ohmic contacts. The issue of unintentional hydrogen passivation of dopants will also be covered - this leads to strong increases in resistivity of p-SiC and GaN, but to large decreases in resistivity of diamond. Recent work on development of wet etches has found recipes for AlN (KOH), while photochemical etching of SiC and GaN has been reported. In the latter cases p-type materials is not etched, which can be a major liability in some devices. The dry etch results obtained with various novel reactors, including ICP, ECR and LE4 will be compared - the high ion densities in the former techniques produce the highest etch rates for strongly-bonded materials, but can lead to preferential loss of N from the nitrides and therefore to a highly conducting surface. This is potentially a major problem for fabrication of dry etched, recessed gate FET structures.« less
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