Ion versus pH sensitivity of ungated AlGaN/GaN heterostructure-based

摘要

We have investigated the pH and ion sensitivity of AlGaN/GaN heterostructure devices; thesendevices are sensitive to the ion concentration rather than to the pH of the solution. Sheet resistancenas a function of pH for calibrated pH solutions and dilute NaOH, HCl, KOH, and NaCl showed annincrease as a function of ionic concentration, regardless of whether the pH was acidic, basic, ornneutral. An increase in resistance corresponds to accumulation of negative ions at the AlGaNnsurface, indicating device selectivity toward the negative ions. We attribute this to the formation ofna double layer at the liquid/semiconductor interface. © 2010 American Institute of Physics.nu0004doi:10.1063/1.3462323