Improvement in Ohmic Properties of Ti/Au Contact to n-type ß-Ga2O3 Using Inductively Coupled Plasma Treatment
(Room Exhibit Hall A)
30 Apr 19
2:30 PM
-
4:00 PM
We investigate the effects of surface treatment using inductively coupled plasma (ICP) on Ohmic properties of contacts to n-type ß-Ga2O3. After removing surface contaminants on n-type ß-Ga2O3, ICP treatments were performed using BCl3 (30 sccm) with a bias power of 150 W and an inductive power of 300 W. For forming Ohmic contact, Ti (20 nm) and Au (80 nm) films were sequentially deposited on ICP-treated n-type ß-Ga2O3, followed by at 500 °C for 1 min. in flowing N2 ambient. Atomic force microscopy results showed the surface degradation caused by ICP treatments was insignificant. The specific contact resistivity, extracted using circular transmission line model combined with cross-bridge Kelvin resistor structure, was measured to be 1.49 × 10-5 and 8.29 × 10-5 Ωcm2 for contacts with and without ICP treatment, respectively. X-ray photoemission spectroscopy results revealed that B-oxide was formed on ICP-treated Ga2O3 surface, which could be associated with chemical reaction between BCl3 and Ga2O3. Such a formation of B-oxide implies that a number of oxygen vacancies, acting as donor for electrons, were produced on n-type ß-Ga2O3 surface, which played a main role in the reduction of specific contact resistivity of Ti/Au contact to n-type ß-Ga2O3.