β-Ga2O3 device reliability is often limited by the stability of metal–semiconductorcontacts at elevated temperature. This thesis evaluates contact behavior through twocomplementarystudies. Study1: Non-alloyedTi/Auohmiccontactcappedwith ALD Al2O3 uses the Al2O3 cap only to suppress ambient interactions (O2/H2O), allowing on-chuck heating in air from room temperature to 500°C to reveal the intrinsic temperature dependence of Rc and Rsh using CTLM. Study 2: Alloyed Ti and Cr based contacts – effect of annealing temperature subjects unpassivated devices to stepwise anneals in dry N2 from 200°C to 500°C; CTLM after each step maps irreversible interface changes and identifies an optimum Ti/Au anneal window of 300°C to 400°C that minimizes Rc. Cr-based contacts are characterized in parallel to assess metallization choice. Together, these results isolate temperature effects from ambient artifacts, define a practical anneal window for Ti/Au, and evaluate Cr as an alternative, providing processing guidance for reliable high- temperature β-Ga2O3 devices.