Student Paper A III-V Field Effect Transistor (FET) with Hafnium Oxide Gate Dielectric for the Detection of Deoxyribonucleic Acid (DNA) Hybridization

Field-portable DNA biosensors have the potential to greatly improve diagnosis of disease, forensic DNA analysis, food safety monitoring, and biowarfare detection. These sensors detect hybridization of complementary strands of DNA, one immobilized onto the sensor substrate and the other free in solution. Most DNA sensors suffer from lack of portability or the inability to process large numbers of samples in parallel. Field effect transistor (FET) based DNA sensors, which detect hybridization by sensing negative charges on target DNA through the field effect, have the potential for both high throughput and portable detection [1]. In this work we present a novel depletion mode FET sensor that incorporates: 1) III-V semiconducting materials, 2) a hafnium oxide gate dielectric, and 3) direct immobilization of DNA to the surface. Our work differs from previously demonstrated FET biosensors that use doped silicon semiconductors with a silicon dioxide gate dielectric and complex crosslinking chemistry between the surface and the DNA [1]. We hypothesize that depletion mode FETs are more sensitive, due to the lower density of states in the III-V materials (AlGaAs/InAlAs) [2]. Further, our novel method of directly immobilizing DNA onto the gate significantly simplifies sensor fabrication and brings DNA closer to the sensor surface. This places the majority of the DNA within one Debye length from the gate oxid