CHARACTERIZATION OF INTERFACE CHARGE AT GA0.52IN0.48P GAAS JUNCTIONS USING CURRENT-VOLTAGE AND CAPACITANCE-VOLTAGE MEASUREMENTS/

Al/i:GaInP/n:GaAs Schottky structures of varying undoped layer thickne sses (100-1000 Angstrom) were grown in situ by gas source molecular be am epitaxy (GSMBE). Effective Schottky barrier heights (phi(bIV)) of 0 .87 +/- 0.02 eV were determined from the current-voltage (I-V) method with ideality factor of < 1.05 which is characteristic of thermionic e mission but a decrease in barrier height (phi(bCV)) With increasing Ga InP thickness as measured by the capacitance-voltage (C-V) method was observed. We found that the plot of phi(bIV) minus phi(bCV) versus GaI nP thickness is a straight line. This can be explained by modeling a p ositive delta sheet charge at the GaInP/GaAs interface which will resu lt in a constant electric field (slope of the above line) with sheet c harge estimated to be 5 x 10(11) cm(-2). This sheet charge is proposed to be the result of ionized donor states at such interface. (C) 1996 American Institute of Physics.