Stability of sulfur-treated n-InP Schottky structures, studied by current–voltage measurements

Electrical properties of n-InP metal–semiconductor diodes with S-treated, annealed S-treated and as-etched (non-treated) surfaces are investigated. 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 remains nearly constant, around 0.6 eV, in the investigated temperature range, whereas for the untreated surfaces, the SBH increases linearly with temperature. The ideality factor, n, is temperature-dependent for the as-etched samples and nearly constant, ≈1.1, for the S-treated contacts. This behavior is discussed in terms of the interfacial layer model. For the non-treated samples, the n versus V curve exhibits a peak around 0.3 V, from which the interface states density can be estimated, with a maximum value of 4×1012 cm−2 eV−1. Such voltage dependence of n has not been observed initially for the S-passivated structures and appears only after prolonged air exposure, with a less pronounced evolution for the annealed samples, showing the beneficial effect on the stability and the contact quality of these structures.