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

This article investigates the applicability of an open-gated high-electron-mobility transistor (HEMT) as a biosensing platform for human serum albumin (HSA). The 3-aminopropyltriethoxysilane (APTES) is a binding molecule to albumin defined by its dielectric constant and 2-nm 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 (0.005–0.06 pg/l) was calculated by the charge deduction method and introduced at the sensing interface to evaluate the sensor response. The sensor performance was extracted for different gate oxides (SiO2, Al2O3, and HfO2) and gate-to-drain distance (
${L}_{\text {GD}}$
= 2, 4, 6, and
$8 \, \mu \text{m}$
) in terms of threshold voltage variation and drain current sensitivity, along with response and recovery time. The proposed device shows a maximum variation in the drain current of 38.12 mA/mm at
${V}_{\text {GS}}$
= -1.5 V and a threshold voltage sensitivity of 65 mV for the Al2O3 gate oxide at
${L} _{\text {GD}}=2 \, \mu \text{m}$
, respectively, for 0.06 pg/l of concentration. The limit of detection (LoD) obtained is 0.94 fg/l for the SiO2 gate oxide at
${V} _{\text {GS}}$
= -1.5 V. All the results have been extracted using the Silvaco Atlas device simulation tool. The sensitivity assessments demonstrate that APTES-functionalized open-gated HEMT can be a good candidate for albumin detection and other biosensing applications.