Effect of oxygen plasma treatment on the performance of A1GaN/GaN ion-sensitive field-effect transistors

摘要

AIGaN/GaN ion-sensitive field-effect transistors (ISFETs) were fabricated and the sensitivity was evaluated with O-2 plasma treatment for different time. For a short-time O-2 plasma treatment, the sensitivity of the AIGaN/GaN ISFET improved to 55.7 mV/pH, which is very close to the theoretical value of 58.7 mV/pH at 23 degrees C. However, with a long-time O-2 plasma treatment, the sensitivity decreased. X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and water contact angle measurement were utilized to characterize the surface conditions. It indicated that, after short-time O-2 plasma treatment, the AIGaN/GaN surface with a rich aluminum oxide is the main reason to improve the sensitivity of AIGaN/GaN ISFET. The surface of the AIGaN barrier layer became much smooth and clean with the water contact angle on the AIGaN surface decreasing to approximately 5-7 degrees. With the O-2 plasma treatment time increasing, the aluminum oxide dominated AIGaN/GaN surface changes to a gallium oxide dominated surface, leading to the decreasing on the ISFET sensitivity. These results suggest that a short-time O-2 plasma treatment is an appreciate technique to improve the device performance of the AIGaN/GaN ISFETs. (C) 2016 Elsevier B.V. All rights reserved.