The influence of electrode on sensitivity of pH sensors fabricated on AlGaN/GaN heterostructures

摘要

In this paper, we report on metallization stack as an ohmic contact to gateless AlGaN/GaN high electron mobility transistors (HEMTs). As compared with Ion-Selective Field Effect Transistor (ISFET) based on Silicon, AlGaN/GaN HEMT has several attractive points for various chemical and biological sensor applications. One of the unique features in AlGaN/GaN, which is a high-density Two Dimensional Electron Gas (2DEG), is known to allow highly sensitive detection of surface phenomenon. Many researchers have elucidated the mechanism and improved sensitivity with perspective of 2DEG. However, there are no researches that explain why Ti/Al/Ti/Au stack is used as an ohmic contact in pH sensors based on AlGaN/GaN HEMTs. We focused on the relationship between ohmic materials on AlGaN/GaN HEMT and sensitivity of pH sensors.