Metal-n-InP Rectifying Properties Enhancement with Zn Based Metallizations and Diffusion at Moderate Annealing Temperatures

Rectifying contacts on n-InP using Zn based metallizations followed by moderate annealing temperature and time were studied. Diffusion of Zn atoms at the metal-semiconductor interface creates a thin p-InP layer. Pseudo-Schottky junctions were obtained with a significant barrier height enhancement, typically 0.2-0.25 eV. The metallization process involved throughout the present work leads to high quality Schottky diodes within a rather simple procedure similar to this generally used to obtain good ohmic contacts. It is shown in particular that the special requirements needed for a lot of electrical measurements (e.g. C-V characteristics or D.L.T.S.) can be matched without any extra complication. The behaviour of Schottky devices was throroughly analysed as a function of the annealing procedure. Best performances were obtained by applying cumulative annealing sequences, increasing the temperature while decreasing the time of exposure. The homogeneity of the structures was attested from a satisfactory agreement between barrier heights deduced either from current or from capacitance measurements. A good linearity of C -2 -V-T curves and low values of the series resistances were also obtained.