A Comparative Study of Vertical and Horizontal p-Type InN Nanowires Grown by MOCVD for an Optoelectronic Application

In this work, structural and optoelectrical properties of vertical and horizontal nanowires are investigated. Both the type of nanowires are realized using MOCVD system. Before MOCVD deposition an In seed layer is deposited using DC sputtering system. Further studies in crystalline properties reveals a probable temperature dependency of nanowire growth direction. Photoluminescence spectra presents the electronic band gap of the grown nanowires to be 0.8 eV. Though the peak positions for both the type are same nearly 1550 nm but the integrated PL intensity of vertical nanowires are found to be higher in comparison to horizontal ones. This can be attributed to the larger active area associated to vertical nanowires. TEM study reveals a very thin native In2O3 layer due to very high reactivity of In in air. Furthermore to study the opto-electronic device applicability photocurrent is measured for both the types of nanowires. Vertical nanowires records a high photocurrent than horizontal. This enhancement in photocurrent can be attributed to higher density of nanowires and larger active area offered by vertical nanowires.