MBE GROWTH AND PROPERTIES OF ALGAAS GAAS ALGAAS SELECTIVELY-DOPED DOUBLE-HETEROJUNCTION STRUCTURES WITH VERY HIGH CONDUCTIVITY

The growth condition and structural parameters to achieve both extremely high mobilities, mu //s and high carrier concentrations, N//s were clarified for AlGaAs/GaAs/AlGaAs selectively-doped double-heterojunction structures. The growth of a relatively low substrate temperature (approx. 530 degree c) and the use of wide GaAs-well were necessary in achieving mu //s greater than 10**5 cm**2/Vs. When the thickness W//s//p of the undoped spacer layers was reduced, N//s was found to increase in accordance with the theory, reaching 2 multiplied by 10**1**2/cm**2 at W//s//p equals 0 A. In contrast, mu //s showed maximum at W//s//p equals 90 A, at which an extremely high conductivity was achieved.