| 摘要 |
PURPOSE:To form a high quality epitaxial layer on a semi-insulated substrate by forming a first semiconductor layer by the epitaxial growth method on a Cr- doped GaAs substrate, then forming a second semiconductor layer which forms the hetero junction with said first layer also by the epitaxial growth method and thereafter removing such second semiconductor layer. CONSTITUTION:A Cr-doped GaAs crystal substrate 1 is washing, degreasing and the surface thereof is etched. Thereafter, it is placed in an MBE apparatus and the surface of said substrate is purified through temperature rise under the vacuum condition and an undoped GaAs layer 2 is formed by the epitaxial growth method. After forming an N type GaAs active layer 3 on said layer and forming Al0.2Ga0.8As layer 4 which forms a hetero junction with the GaAs layer 3 by the epitaxial growth method, only the Al0.2Ga0.8As layer 4 is etched by the iodo etchant. Since Cr segregated at the surface is all included in the Al0.2Ga0.8As layer 4, it is perfectly removed by such etching and an N type GaAs active layer 3 is not adversely influenced by the etching selectivity. After this process, a GaAs MESFET is completed by forming the source, drain and gate electrodes. |
