Performance Assessment of AlGaN/GaN HEMT for Human Serum Albumin Detection Using Charge Deduction Methodology

This article investigates the applicability of open gated high electron mobility transistor (HEMT) as a bio-sensing platform for human serum albumin (HSA). The 3-Aminopropyltriethoxysilane (APTES) is a binding molecule to Albumin defined by its dielectric constant and 2nm of thickness in the open gate region. The APTES functionalization and biomolecule immobilization have been confirmed by the change in drain current characteristics. The charge equivalent for a broad range of albumin concentrations (0.005 pg/l to 0.06 pg/l) was calculated by charge deduction method and introduced at sensing interface to evaluate the sensor response. The sensor performance was extracted for different gate oxides (SiO ₂ , Al ₂ O ₃ , HfO ₂ ) and gate to drain distance (L _GD = 2 μm, 4 μm, 6 μm, and 8 μm) in terms of threshold voltage variation, drain current sensitivity, along with response and recovery time. The proposed device shows a maximum variation in drain current of 38.12 mA/mm at V _GS = -1.5 V and a threshold voltage sensitivity of 65 mV for the Al ₂ O ₃ gate oxide at L _GD = 2μm, respectively for 0.06 pg/l of concentration. The limit of detection obtained is 0.94 fg/l for SiO ₂ gate oxide at V _GS = -1.5 V. All the results have been extracted using the Silvaco Atlas device simulation tool. The sensitivity assessments demonstrates that APTES functionalized open gated HEMT can be a good candidate for albumin detection and other biosensing applications.