| 摘要 |
PROBLEM TO BE SOLVED: To improve electron mobility of HEMT even by doping at the same carrier concentration in comparison with the conventional technology, by optimizing the balance of film thickness between an AlGaAs layer and a GaAs layer forming a spacer layer. SOLUTION: An In<SB>y</SB>Ga<SB>(1-y)</SB>As layer with a mixed crystal ratio y of 0.15-0.30 is formed as a channel layer 5 of HEMT at a film thickness of 5-15 nm, and an AlGaAs layer 6a (or 4a) and a GaAs layer 6b (or 4b) are combined and used for a spacer layer 6 (or 4). An Al<SB>x</SB>Ga<SB>(1-x)</SB>As layer with a mixed crystal ratio x of 0.26-0.50 is formed at a film thickness of 0.1-7.0 nm as the AlGaAs layer 6a or 4a on the side of a carrier supply layer 7 (or 3), and the GaAs layer 6b (4b) is formed at a film thickness of 0.1-7.0 nm on the side of the channel layer 5. In this case, the spacer layer 6 (or 4) including the AlGaAs layer and the GaAs layer does not exceed 10 nm in thickness. COPYRIGHT: (C)2007,JPO&INPIT
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