{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,19]],"date-time":"2026-02-19T02:26:27Z","timestamp":1771467987228,"version":"3.50.1"},"reference-count":45,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2020,12,2]],"date-time":"2020-12-02T00:00:00Z","timestamp":1606867200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Grant-in-Aids for Scientific Research, Japan","award":["18H01548(B)"],"award-info":[{"award-number":["18H01548(B)"]}]},{"name":"Grant-in-Aids for Scientific Research","award":["19H02204(B)"],"award-info":[{"award-number":["19H02204(B)"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The theoretical temporal resolution limit tT of a silicon photodiode (Si PD) is 11.1 ps. We call \u201csuper temporal resolution\u201d the temporal resolution that is shorter than that limit. To achieve this resolution, Germanium is selected as a candidate material for the photodiode (Ge PD) for visible light since the absorption coefficient of Ge for the wavelength is several tens of times higher than that of Si, allowing a very thin PD. On the other hand, the saturation drift velocity of electrons in Ge is about 2\/3 of that in Si. The ratio suggests an ultra-short propagation time of electrons in the Ge PD. However, the diffusion coefficient of electrons in Ge is four times higher than that of Si. Therefore, Monte Carlo simulations were applied to analyze the temporal resolution of the Ge PD. The estimated theoretical temporal resolution limit is 0.26 ps, while the practical limit is 1.41 ps. To achieve a super temporal resolution better than 11.1 ps, the driver circuit must operate at least 100 GHz. It is thus proposed to develop, at first, a short-wavelength infrared (SWIR) ultra-high-speed image sensor with a thicker and wider Ge PD, and then gradually decrease the size along with the progress of the driver circuits.<\/jats:p>","DOI":"10.3390\/s20236895","type":"journal-article","created":{"date-parts":[[2020,12,2]],"date-time":"2020-12-02T20:25:49Z","timestamp":1606940749000},"page":"6895","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Toward the Super Temporal Resolution Image Sensor with a Germanium Photodiode for Visible Light"],"prefix":"10.3390","volume":"20","author":[{"given":"Nguyen Hoai","family":"Ngo","sequence":"first","affiliation":[{"name":"School of Science and Engineering, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga 525-8577, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4198-4208","authenticated-orcid":false,"given":"Anh Quang","family":"Nguyen","sequence":"additional","affiliation":[{"name":"School of Electronics and Telecommunications, Hanoi University of Science and Technology, 1 Dai Co Viet, Bach Khoa, Hai Ba Trung, Hanoi 100803, Vietnam"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fabian M.","family":"Bufler","sequence":"additional","affiliation":[{"name":"IMEC, 3001 Leuven, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yoshinari","family":"Kamakura","sequence":"additional","affiliation":[{"name":"Faculty of Information Science and Technology, Osaka Institute of Technology, Hirakata Campus, 1-79-1 Kitayama, Hirakata City, Osaka 573-0196, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hideki","family":"Mutoh","sequence":"additional","affiliation":[{"name":"Link Research Corporation, 291-4, Kuno, Odawara-shi, Kanagawa 250-0055, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Takayoshi","family":"Shimura","sequence":"additional","affiliation":[{"name":"Graduate School of Engineering, Osaka University, 1-1 Yamada-oka, Suita, Osaka 565-0871, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Takuji","family":"Hosoi","sequence":"additional","affiliation":[{"name":"Graduate School of Engineering, Osaka University, 1-1 Yamada-oka, Suita, Osaka 565-0871, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Heiji","family":"Watanabe","sequence":"additional","affiliation":[{"name":"Graduate School of Engineering, Osaka University, 1-1 Yamada-oka, Suita, Osaka 565-0871, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Philippe","family":"Matagne","sequence":"additional","affiliation":[{"name":"IMEC, 3001 Leuven, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1814-7767","authenticated-orcid":false,"given":"Kazuhiro","family":"Shimonomura","sequence":"additional","affiliation":[{"name":"School of Science and Engineering, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga 525-8577, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kohsei","family":"Takehara","sequence":"additional","affiliation":[{"name":"Department of Civil and Environmental Engineering, School of Science and Engineering, Kindai University, 3-4-1 Kowakae, Higashi-Osaka, Osaka 577-8502, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Edoardo","family":"Charbon","sequence":"additional","affiliation":[{"name":"Advanced Quantum Architecture Laboratory, EPFL, Rue de la Maladi\u00e8re 71b, Case Postale 526, CH-2002 Neuch\u00e2tel, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Takeharu Goji","family":"Etoh","sequence":"additional","affiliation":[{"name":"School of Science and Engineering, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga 525-8577, Japan"},{"name":"Graduate School of Engineering, Osaka University, 1-1 Yamada-oka, Suita, Osaka 565-0871, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2020,12,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Etoh, T.G., Nguyen, A.Q., Kamakura, Y., Shimonomura, K., Le, T.Y., and Mori, N. 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