Optimization of (In)GaN Heterostructures for Sensing Applications

Abstract

Herein, the optimization of (In)GaN heterostructures for chemical sensing is presented. The metalorganic vapor phase epitaxy (MOVPE)‐grown sensor consists of an InxGa1−xN quantum well (QW) placed close to the surface of a GaN substrate with a thin GaN cap layer on top. The photoluminescence (PL) wavelength of this QW is sensitive to surface potential changes and thus its optical signal is used as sensor response. Simulations are performed with nextnano to improve its sensitivity. Sensor parameters such as the cap layer thickness d, QW thickness Lz, background buffer layer doping concentration N, and indium concentration x of the QW are varied. It is found that a thin cap layer, together with high background doping and medium QW thickness, is ideal. The indium content does not show a strong influence on sensitivity. The trends found in the simulations are mostly confirmed in real‐world experiments performed in a chemical sensing setup, yet quantitative deviations exist.

Highly Sensitive Hydrogen Sulfide Sensor Based on GaN/GaInN Heterostructure

“…Simulation results presented in ref. [13] have shown a general trend of increased sensitivity with increasing doping concentration up to a certain optimal value. However, surprisingly, the measured results for 100 ppb of H 2 S sensing showed an opposite trend as can be seen in Figure 5 (top).…”

“…These results are consistent with previously published work. [11,13] In Figure 3, bottom, the root mean square (RMS) surface roughness (ranging from about 6-10 nm) and the covered area percentage of the gold layer is shown. Larger pores on the metal surface increase the surface-to-volume ratio and have shown improved sensitivity.…”

“…Semiconductor-based sensors with their potential for miniaturization and cost reduction could provide a solution for this issue. The material properties of group-III nitrides not only make them suitable for applications such as high-power electronics, laser diodes, and light-emitting diodes (LEDs) but also for use in gas [9][10][11] and chemical [12][13][14] sensing. The sensor structures used in this study are reactive to the changes in the surface potential due to the adsorption or desorption of gas molecules.…”