INALAS/INGAAS HETEROJUNCTION STRUCTURE SEMICONDUCTOR DEVICE AND FIELD EFFECT TRANSISTOR USING IT

摘要

PURPOSE:To achieve a high mobility by increasing In composition ratio of InGaAs channel layer and then enable reduction in electron density accompanying it to be suppressed. CONSTITUTION:In a heterojunction structure of InGaAs 4 and InAlAs 5.6, each in composition ratio is 0.8 and 0.65 and is larger at InGaAs layer 4 where a two dimensional electron gas 4a is formed, thus achieving a high mobility of the InGaAs layer 4 and suppressing reduction in an amount of band discontinuity and reduction in density of electrons. With layers 5, 6, and 7 which are formed on the InGaAs layer 4 with the In composition ratio of 0.65, the total film thickness is set to a critical film thickness for preventing generation of transformation accompanying a lattice mismatching with the InGaAs layer 4 and the lattice mismatching between the InGaAs layer 4 and the semi-insulation GaAs substrate 1 is absorbed and relaxed by an InGaAs graded buffer layer 2.