STABILITY OF SULFUR-TREATED N-INP SCHOTTKY STRUCTURES, STUDIED BY CURRENT-VOLTAGE MEASUREMENTS

Electrical properties of n-InP metal-semiconductor diodes with S-treat ed, annealed S-treated and as-etched (non-treated) surfaces are invest igated. The schottky barrier heights (SBH) are estimated from current- voltage (I-V) and capacitance-voltage (C-V) measurements made between 220 and 320 K. For S-passivated contacts, it is shown that the SBH rem ains nearly constant, around 0.6 eV, in the investigated temperature r ange, whereas for the untreated surfaces, the SBH increases linearly w ith temperature. The ideality factor, n, is temperature-dependent for the as-etched samples and nearly constant, approximate to 1.1, for the S-treated contacts. This behavior is discussed in terms of the interf acial layer model. For the non-treated samples, the n versus V curve e xhibits a peak around 0.3 V, from which the interface states density c an be estimated, with a maximum value of 4 x 10(12) cm(-2) eV(-1). Suc h voltage dependence of n has not been observed initially for the S-pa ssivated structures and appears only after prolonged air exposure, wit h a less pronounced evolution for the annealed samples, showing the be neficial effect on the stability and the contact quality of these stru ctures. (C) 1998 Published by Elsevier Science S.A. All rights reserve d.