{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,1]],"date-time":"2026-02-01T06:26:40Z","timestamp":1769927200190,"version":"3.49.0"},"reference-count":31,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2017,7,21]],"date-time":"2017-07-21T00:00:00Z","timestamp":1500595200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The UV-to-visible rejection ratio is one of the important figure of merits of GaN-based UV photodetectors. For cost-effectiveness and large-scale fabrication of GaN devices, we tried to grow a GaN epitaxial layer on silicon substrate with complicated buffer layers for a stress-release. It is known that the structure of the buffer layers affects the performance of devices fabricated on the GaN epitaxial layers. In this study, we show that the design of a buffer layer structure can make effect on the UV-to-visible rejection ratio of GaN UV photodetectors. The GaN photodetector fabricated on GaN-on-silicon substrate with a step-graded AlxGa\u2212xN buffer layer has a highly-selective photoresponse at 365-nm wavelength. The UV-to-visible rejection ratio of the GaN UV photodetector with the step-graded AlxGa1\u2212xN buffer layer was an order-of-magnitude higher than that of a photodetector with a conventional GaN\/AlN multi buffer layer. The maximum photoresponsivity was as high as 5 \u00d7 10\u22122 A\/W. This result implies that the design of buffer layer is important for photoresponse characteristics of GaN UV photodetectors as well as the crystal quality of the GaN epitaxial layers.<\/jats:p>","DOI":"10.3390\/s17071684","type":"journal-article","created":{"date-parts":[[2017,7,21]],"date-time":"2017-07-21T10:45:48Z","timestamp":1500633948000},"page":"1684","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":24,"title":["Selectively Enhanced UV-A Photoresponsivity of a GaN MSM UV Photodetector with a Step-Graded AlxGa1\u2212xN Buffer Layer"],"prefix":"10.3390","volume":"17","author":[{"given":"Chang-Ju","family":"Lee","sequence":"first","affiliation":[{"name":"School of Electronics Engineering, College of IT Engineering, Kyungpook National University, Daegu 41566, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chul-Ho","family":"Won","sequence":"additional","affiliation":[{"name":"School of Electronics Engineering, College of IT Engineering, Kyungpook National University, Daegu 41566, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jung-Hee","family":"Lee","sequence":"additional","affiliation":[{"name":"School of Electronics Engineering, College of IT Engineering, Kyungpook National University, Daegu 41566, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sung-Ho","family":"Hahm","sequence":"additional","affiliation":[{"name":"School of Electronics Engineering, College of IT Engineering, Kyungpook National University, Daegu 41566, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hongsik","family":"Park","sequence":"additional","affiliation":[{"name":"School of Electronics Engineering, College of IT Engineering, Kyungpook National University, Daegu 41566, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2017,7,21]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"7433","DOI":"10.1063\/1.362677","article-title":"Semiconductor Ultraviolet Detectors","volume":"79","author":"Razeghi","year":"1996","journal-title":"J. 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