A comparative study of Ti and Cr based p-ohmic contacts on high power GaAs laser diodes open site


Date: Jun, 2018
A comparative study of Ti and Cr based p-ohmic contacts on high power GaAs laser diodes

The present work involves a comparison of sequentially evaporated Ti/Pt/Au and Cr/Au p-ohmic contacts for high power laser diode fabrication. Subsequently, the contacts were annealed at 440 °C in furnace annealing under N2 ambient and their surfaces were evaluated by optical and electron microscopy. The specific contact resistivity of the contacts was determined by circular transfer length method (c-TLM). Secondary ion mass spectroscopy (SIMS) analysis of the annealed contacts indicates considerable intermixing of the metal and Ga atoms across the interface for Cr/Au contact. On the other hand, insignificant intermixing of atoms was observed in Ti based contacts. The electrical and optical characteristics of the laser diodes formed with Ti/Pt/Au ohmic contact suggest superior performance compared to the diode formed with Cr/Au contact.