Titanium nitride: A new Ohmic contact material for n-type CdS

Abstract

In devices based on CdS, indium is often used to make Ohmic contacts. Since indium is scarce and expensive, suitable replacement materials need to be found. In this work, we show that sputtered titanium nitride forms an Ohmic contact with n-type CdS. The CdS films, deposited with chemical bath deposition, have a hexagonal crystal structure and are polycrystalline, mostly with a (002) texture. The thickness of the films is ∼600 nm, and the donor density is 1.9 × 1016 cm−3. The donor density increases to 1.5 × 1017 cm−3 upon annealing. The contact resistivity of sputtered TiN on CdS is found to be 4.7 ± 0.6 Ω cm2. This value is sufficiently small to avoid large resistive losses in most CdS device applications. To demonstrate the use of TiN in a CdS device, a Au/CdS/TiN Schottky diode was constructed. The diode has a potential barrier of 0.69 V and an ideality factor of 2.2.