Vapor growth of InP for MESFET’S
Epitaxial layers of InP have been grown by the conventional In/PCl3/H{ion2} technique. With the aim of fabricating FET’s structures, we have studied the growth of low doped buffer layers and the doping by H2S. It has been shown, that the purity of the layers increases from experiment to experiment and that low doped layers, in the 1013 – 1014 cm-3 range, are obtained after growth of about 10 layers. Evidence for the purity of these layers have been obtained from Hall, photoluminescence and SIMS measurements. Cr and Fe outdiffusion from the substrate has been studied by SIMS. Fe is found to diffuse from the substrates, even in the case of substrates which are not intentionally doped with Fe. Some FET’s have been fabricated on epitaxial structures with and without buffer layers: the static characteristics of the transistors are encouraging (IDss = 24 mA, gm = 19 mS for a gate of 2 μm and 200 μm in length and width, respectively); the pinch-off is better in devices fabricated from structures with buffer layers.