Effects of growth temperatures on the characteristics of n-GaN nanorods-graphene hybrid structures

The effects of different growth temperatures of n-GaN nanorods (NRs) on the material and electrical properties of n-GaN NRs-graphene hybrid device structures are being demonstrated for the first time. A high quality graphene transfer method was applied for transferring the graphene layer on Si (1 1 1) substrate and n-GaN NRs were synthesized on the graphene layer on Si using a metal organic chemical vapor deposition (MOCVD) process of high V/III ratio. No metal-catalyst or droplet seeds were formed when growing n-GaN NRs. The growth temperature of the n-GaN NRs was varied from 860 °C to 900 °C. Raman spectroscopy confirmed the prominent existence of an undamaged graphene layer in all of the highly-matched hybrid device structures under study. Improvement in the structural, crystalline and material properties was established from FE-SEM, XRD and PL studies for the hybrid structure where n-GaN NRs were grown at 890 °C. The same hybrid structure also showed a ten-fold enhancement in photocurrent along with increased sensitivity and photoresponsivity. Therefore, it can be concluded that a suitable growth temperature of n-GaN NRs is the most important factor for the fabrication of high quality n-GaN NRs-graphene hybrid structures.