Author
Muhammad Asif Khan
Bio: Muhammad Asif Khan is an academic researcher from University of South Carolina. The author has contributed to research in topics: Light-emitting diode & Nitride. The author has an hindex of 23, co-authored 31 publications receiving 1873 citations.
Papers
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Sandia National Laboratories1, University of California, Davis2, Massachusetts Institute of Technology3, Cornell University4, United States Army Research Laboratory5, Ohio State University6, University of California, Santa Barbara7, Boston University8, North Carolina State University9, Purdue University10, Georgia Institute of Technology11, Michigan State University12, Air Force Research Laboratory13, National Institute of Information and Communications Technology14, University of South Carolina15, United States Naval Research Laboratory16, Arizona State University17, University of Illinois at Urbana–Champaign18, Vanderbilt University19
TL;DR: The UWBG semiconductor materials, such as high Al‐content AlGaN, diamond and Ga2O3, advanced in maturity to the point where realizing some of their tantalizing advantages is a relatively near‐term possibility.
Abstract: J. Y. Tsao,* S. Chowdhury, M. A. Hollis,* D. Jena, N. M. Johnson, K. A. Jones, R. J. Kaplar,* S. Rajan, C. G. Van de Walle, E. Bellotti, C. L. Chua, R. Collazo, M. E. Coltrin, J. A. Cooper, K. R. Evans, S. Graham, T. A. Grotjohn, E. R. Heller, M. Higashiwaki, M. S. Islam, P. W. Juodawlkis, M. A. Khan, A. D. Koehler, J. H. Leach, U. K. Mishra, R. J. Nemanich, R. C. N. Pilawa-Podgurski, J. B. Shealy, Z. Sitar, M. J. Tadjer, A. F. Witulski, M. Wraback, and J. A. Simmons
785 citations
Patent•
03 Mar 1993
TL;DR: In this article, a high electron mobility transistor is disclosed, which takes advantage of the increased mobility due to a two dimensional electron gas occurring in GaN/Al x Ga 1-x N heterojunctions.
Abstract: A high electron mobility transistor is disclosed, which takes advantage of the increased mobility due to a two dimensional electron gas occurring in GaN/Al x Ga 1-x N heterojunctions. These structures are deposited on basal plane sapphire using low pressure metalorganic chemical vapor deposition. The electron mobility of the heterojunction is approximately 620 cm 2 per volt second at room temperature as compared to 56 cm 2 per volt second for bulk GaN of the same thickness deposited under identical conditions. The mobility of the bulk sample peaked at 62 cm 2 per volt second at 180° K. and decreased to 19 cm 2 per volt second at 77° K. The mobility for the heterostructure, however, increased to a value of 1,600 cm 2 per volt second at 77° K. and saturated at 4° K.
165 citations
Patent•
27 Sep 2001
TL;DR: In this article, a method and structure for producing nitride-based heterostructure devices having substantially lower reverse leakage currents and performance characteristics comparable to other conventional devices was proposed, which includes placing one or more layers of nitride based compounds over a substrate.
Abstract: A method and structure for producing nitride based heterostructure devices having substantially lower reverse leakage currents and performance characteristics comparable to other conventional devices. The method and structure include placing one or more layers of nitride-based compounds over a substrate. Additionally, a dielectric layer including silicon dioxide is placed over the nitride-based layers.
114 citations
Patent•
17 May 1991
TL;DR: In this article, a high electron mobility transistor is disclosed, which takes advantage of the increased mobility due to a two dimensional electron gas occurring in GaN/Al x Ga 1-x N heterojunctions.
Abstract: A high electron mobility transistor is disclosed, which takes advantage of the increased mobility due to a two dimensional electron gas occurring in GaN/Al x Ga 1-x N heterojunctions. These structures are deposited on basal plane sapphire using low pressure metalorganic chemical vapor deposition. The electron mobility of the heterojunction is aproximately 620 cm 2 per volt second at room temperature as compared to 56 cm 2 per volt second at 180° K. and decreased to 19 cm 2 per volt second at 77° K. The mobility for the heterostructure, however, increased to a value of 1,600 cm 2 per volt second at 77° K. and saturated at 4° K.
105 citations
TL;DR: In this paper, a pn-junction ultraviolet light-emitting diode (LED) with peak emission at 363 nm using a-plane GaN-AlGaN multiple quantum wells over r-plane sapphire.
Abstract: We report a pn-junction ultraviolet light-emitting diode (LED) with peak emission at 363 nm using a-plane GaN-AlGaN multiple quantum wells over r-plane sapphire. The peak emission wavelength does not shift with increasing pump currents-therefore establishing the feasibility of high-efficiency non-polar light emitting devices.
100 citations
Cited by
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Journal Article•
28,685 citations
TL;DR: In this paper, a general review of the advances in widebandgap semiconductor photodetectors is presented, including SiC, diamond, III-nitrides and ZnS.
Abstract: Industries such as the automotive, aerospace or military, as well as environmental and biological research have promoted the development of ultraviolet (UV) photodetectors capable of operating at high temperatures and in hostile environments. UV-enhanced Si photodiodes are hence giving way to a new generation of UV detectors fabricated from wide-bandgap semiconductors, such as SiC, diamond, III-nitrides, ZnS, ZnO, or ZnSe. This paper provides a general review of latest progresses in wide-bandgap semiconductor photodetectors.
1,194 citations
Patent•
25 Mar 2002
TL;DR: In this paper, the authors propose a system and method for communicating information between a first party and a second party, comprising the steps of receiving, by an intermediary, an identifier of desired information and accounting information for a transaction involving the information from the first party, and negotiating, by the intermediary, a comprehension function for obscuring at least a portion of the information communicated between the first parties and the second parties.
Abstract: A system and method for communicating information between a first party and a second party, comprising the steps of receiving, by an intermediary, an identifier of desired information and accounting information for a transaction involving the information from the first party, transmitting an identifier of the first party to the second party, and negotiating, by the intermediary, a comprehension function for obscuring at least a portion of the information communicated between the first party and the second party. The data transmission may be made secure with respect to the intermediary by providing an asymmetric key or direct key exchange for encryption of the communication between the first and second party. The data transmission may be made secure with respect to the second party by maintaining the information in encrypted format at the second party, with the decryption key held only by the intermediary, and transmitting a secure composite of the decryption key and a new encryption key to the second party for transcoding of the data record, and providing the new decryption key to the first party, so that the information transmitted to the first party can be comprehended by it.
1,193 citations
TL;DR: In this paper, the Auger recombination coefficient in quasi-bulk InxGa1−xN (x∼9%−15%) layers grown on GaN (0001) is measured by a photoluminescence technique.
Abstract: The Auger recombination coefficient in quasi-bulk InxGa1−xN (x∼9%–15%) layers grown on GaN (0001) is measured by a photoluminescence technique. The samples vary in InN composition, thickness, and threading dislocation density. Throughout this sample set, the measured Auger coefficient ranges from 1.4×10−30to2.0×10−30cm6s−1. The authors argue that an Auger coefficient of this magnitude, combined with the high carrier densities reached in blue and green InGaN∕GaN (0001) quantum well light-emitting diodes (LEDs), is the reason why the maximum external quantum efficiency in these devices is observed at very low current densities. Thus, Auger recombination is the primary nonradiative path for carriers at typical LED operating currents and is the reason behind the drop in efficiency with increasing current even under room-temperature (short-pulsed, low-duty-factor) injection conditions.
1,124 citations
Patent•
14 Apr 2000
TL;DR: In this article, the authors proposed a method for sequential chemical vapor deposition by employing a reactor operated at low pressure, a pump to remove excess reactants, and a line to introduce gas into the reactor through a valve.
Abstract: The present invention provides for sequential chemical vapor deposition by employing a reactor operated at low pressure, a pump to remove excess reactants, and a line to introduce gas into the reactor through a valve. A first reactant forms a monolayer on the part to be coated, while the second reactant passes through a radical generator which partially decomposes or activates the second reactant into a gaseous radical before it impinges on the monolayer. This second reactant does not necessarily form a monolayer but is available to react with the monolayer. A pump removes the excess second reactant and reaction products completing the process cycle. The process cycle can be repeated to grow the desired thickness of film.
899 citations