DIFFERENCES IN THE GROWTH-MECHANISM OF INXGA1-XAS ON GAAS STUDIED BY THE ELECTRICAL-PROPERTIES OF AL0.3GA0.7AS/INXGA1-XAS HETEROSTRUCTURES (0.2-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-0.4)

The growth modes, three dimensional (3d) or two dimensional (2d), of InGaAs layers have been studied by their influences on electrical properties of InGaAs composed heterostructures. We have grown AlGaAs/InGaAs heterostructures by MBE with InAs mole fractious (x) ranging form 0.2 to 0.4. For x<0.25 the layers grow in 2d growth mode. Exceeding the critical layer thickness (CLT) inverted HEMT structures show highly anisotropic electron mobilities with higher mobility in <011> direction. For x>0.25 the layers grow in 3d growth mode which degrades the transport properties of AlGaAs/InGaAs/GaAs HEMT structures stronger than of inverted GaAs/lnGaAs/AlGaAs KEMT structures. Higher electron mobility is observed in <01-1> direction.