Low resistive InGaN film grown by metalorganic chemical vapor deposition

Indium gallium nitride (InGaN) samples were grown on sapphire substrate with low temperature GaN buffer by metalorganic chemical vapor deposition (MOCVD) under varying growth conditions, such as temperature, pressure and ammonia flow. Although high indium composition is considered as indispensable parameter for sheet carrier concentration (n_s) and low sheet resistance (R_s), our outcomes disclose that higher indium composition in InGaN film doesn't always have high n_s and low R_s. Acceptor nature of carbon related defects, a major trapping sites for electrons, plays a crucial role to limit the carrier concentrations in the InGaN specially grown at low pressure, low temperature and low ammonia flow. Furthermore, study of metal contacts deposited on the grown samples by transmission line method (TLM) shows that carrier concentration is the most important factor to obtain low contact resistance. The measured contact resistance for the sample with 4.5× 10¹⁶ cm² carrier concentration is 0.13 Ωmm which is among the lowest contact resistance for GaN based materials grown by MOCVD. This proves that the use of InGaN in source and drain contact region can surpassingly reduce contact resistance and significantly improve device performance of AlGaN/GaN device.