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First-principles investigations of c...

Lyons, John Lambert.

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First-principles investigations of conductivity control in wide-band-gap semiconductors.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	First-principles investigations of conductivity control in wide-band-gap semiconductors./
Author:	Lyons, John Lambert.
Description:	161 p.
Notes:	Source: Dissertation Abstracts International, Volume: 74-06(E), Section: B.
Contained By:	Dissertation Abstracts International74-06B(E).
Subject:	Engineering, Materials Science. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3553757
ISBN:	9781267934123

First-principles investigations of conductivity control in wide-band-gap semiconductors.
Lyons, John Lambert.

First-principles investigations of conductivity control in wide-band-gap semiconductors. - 161 p.

Source: Dissertation Abstracts International, Volume: 74-06(E), Section: B.

Thesis (Ph.D.)--University of California, Santa Barbara, 2012.

The wide-band-gap semiconductors GaN, AlN, and ZnO have properties that make them attractive candidates for fabricating light-emitting diodes, laser diodes, transistors and solar cells. With band gaps in the visible and ultraviolet, these materials and their alloys can emit and absorb in important regions of the electromagnetic spectrum. Despite the promise of these wide-band-gap semiconductors, their electronic conductivity cannot be completely controlled. In this work, we investigate the lack of conductivity control in these materials using first-principles calculations.

ISBN: 9781267934123Subjects--Topical Terms:

1017759
Engineering, Materials Science.

First-principles investigations of conductivity control in wide-band-gap semiconductors.
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020 $a 9781267934123
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100 1 $a Lyons, John Lambert. $3 2093556
245 1 0 $a First-principles investigations of conductivity control in wide-band-gap semiconductors.
300 $a 161 p.
500 $a Source: Dissertation Abstracts International, Volume: 74-06(E), Section: B.
500 $a Adviser: Chris G. Van de Walle.
502 $a Thesis (Ph.D.)--University of California, Santa Barbara, 2012.
520 $a The wide-band-gap semiconductors GaN, AlN, and ZnO have properties that make them attractive candidates for fabricating light-emitting diodes, laser diodes, transistors and solar cells. With band gaps in the visible and ultraviolet, these materials and their alloys can emit and absorb in important regions of the electromagnetic spectrum. Despite the promise of these wide-band-gap semiconductors, their electronic conductivity cannot be completely controlled. In this work, we investigate the lack of conductivity control in these materials using first-principles calculations.
520 $a We first focus on sources of unintentional n-type conductivity. The sources of such conductivity have long remained unknown, and high concentrations of donors make it more difficult to achieve full control of the conductivity of wide-band-gap semiconductors. We have found that silicon, a common impurity in ZnO, acts as a shallow donor and likely contributes to background n-type conductivity.
520 $a Another shortcoming of these materials is that they are difficult, and sometimes impossible, to dope p type. This is a major barrier, since optoelectronic devices require both p-type and n-type material. Group-V impurities, which substitute on the anion site, are commonly thought to be attractive p-type dopants, especially for ZnO. We find these acceptors lead to highly localized, atomic-like states, making them ineffective dopants. Nitrogen, often touted as a promising acceptor in ZnO, is instead found to be an exceedingly deep acceptor that cannot lead to p-type conductivity. Carbon, a common impurity in the nitride semiconductors, exhibits similar behavior. We calculate characteristic optical signals for these acceptors, allowing for experimental verification of our predictions.
520 $a Finally, we investigate how defect-trapped holes can limit the effectiveness of cation-site acceptors. We find that Mg, the only p-type dopant for GaN, features a localized hole despite being an effective acceptor. In AlN, Mg is also highly localized, hampering hole conductivity in this material. In ZnO, Group-I acceptors such as Li, also trap holes, making them inefficient dopants, and limiting the prospects for achieving p-type ZnO.
520 $a Overall, we find that our results can explain the difficulties in improving the doping efficiency of Mg-doped GaN, and why alternative dopants are not effective. Our results indicate that substitutional acceptors in ZnO are deep defects, and demonstrate why p-type doping of ZnO is currently impossible.
590 $a School code: 0035.
650 4 $a Engineering, Materials Science. $3 1017759
650 4 $a Physics, General. $3 1018488
650 4 $a Engineering, General. $3 1020744
690 $a 0794
690 $a 0605
690 $a 0537
710 2 $a University of California, Santa Barbara. $b Materials. $3 1034108
773 0 $t Dissertation Abstracts International $g 74-06B(E).
790 $a 0035
791 $a Ph.D.
792 $a 2012
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3553757