Process Design for Non-Alloyed Contacts to InP-Based Laser Devices

Abstract

ABSTRACTPl/Ti and W thin films on n- and p- type InP and related materials have been investigated for potential use as a refractory ohmic contacts for conventional, single-side coplanar contacted and self-aligned barrier hetcrostructurc laser devices. Pt and Ti films were deposited sequentially by electron gun evaporation, while the W layer was rf sputtered, both onto p+ -In0.53Ga0.47As (Zn doped 5×l018cm−3) and n−- InP (S doped, 5×l018cm−3). The deposition parameters of the two metal systems were optimized to produce adherent films with the lowest possible induced stress. Almost all the studied systems performed as ohmic contacts already as-deposited and were heat treated by means of rapid thermal processing in the temperature range of 300–900°C. The final contact processing conditions were tuned to provide the lowest possible contact resistance values accompanied by low mechanical stress and stable microstructure.