| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-electron mobility transistor comprising a channel layer in which a high-electron mobility is attained in a low-electric field and impact ionization is restrained at high fields. SOLUTION: The high-electron mobility transistor comprises a non-doped second channel layer 3, composed of In1-x (Al1-z Gaz )x As (where a composition ratios of Al is 0.05-0.5 of (z-1)), a non-doped first channel layer 4 composed of In1-x Gax As which lattice-matches with InP, and an impurity-doped electron supply layer 6 composed of In1-y Aly As which lattice-matches to InP, which are formed on an InP substrate. A sufficient difference in the energy level of a conduction band is gained between the first channel of In1-x Gax As and the n-type In1-y Aly As electron supply layer, thereby increasing the concentration of a two-dimensional electron gas. Also, the high-speed characteristics at the low-electric field is achieved by he high-electron mobility of In1-x Gax As. Furthermore, the second channel layer of In1-x (Al1-z Gaz )x As is formed on a buffer layer side, so that the enhancement of a drain conductance caused by impact ionization in the high-electric field can be prevented.
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