Physical investigation of trap-related effects in power HFETs and their reliability implications |
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Authors: | Mazzanti A Verzellesi G Sozzi G Menozzi R Lanzieri C Canali C |
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Affiliation: | Dipt. di Ingegneria dell'Informazione, Modena Univ.; |
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Abstract: | This paper presents a detailed physical investigation of trapping effects in GaAs power HFETs. Two-dimensional numerical simulations, performed using a hydrodynamic model that includes impact ionization, are compared with experimental results of fresh as well as hot-carrier-stressed HFETs in order to gain insight of intertwined phenomena such as the kink in the dc output curves, the hot-carrier degradation of the drain current, and the impact-ionization-dominated reverse gate current. Thoroughly consistent results show that: 1) the kink effect is dominated by the traps at the source-gate recess surface; and 2) as far as the hot-carrier degradation is concerned, only a simultaneous increase of the trap density at the drain-gate recess surface and at the channel-buffer interface (again at the drain side of the channel) is able to account for the simultaneous decrease of the drain current and the increase of the impact-ionization-dominated reverse gate current. |
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