Impact of Device Technology Processes on the Surface Properties and Biocompatibility of Group III Nitride Based Sensors

In this work we have investigated the impact of typical device processing steps on the surface properties (roughness, chemical composition, contact angle to water) of group III‐nitride based chemical sensors with emphasis on the electrical performance of the sensor and the biocompatibility. Basic sensing device is an AlGaN/GaN high electron mobility transistor. The widely distributed mammalian cell cultures HEK 293FT and CHO‐K1 served as biological model systems. The processing of the devices had only little influence on the cell growth onto the sensor. In all cases it was superior to silicon surfaces. Fluorine dry etching smoothes the surface and forms an oxide, which improves the electrical properties of the AlGaN/GaN sensor. In contrast, autoclave treatment enhances the carbon contamination with negative impact on the sensor properties and increased the contact angle to water. For all other treatments the contact angle recaptures a value of about 50 ± 5° after exposure to air or water droplets for some hours due to the contamination by hydrocarbons.