Hydrogen influence on electrical properties of Pt-contacted α-Ga₂O₃/ϵ-Ga₂O₃ structures grown on patterned sapphire substrates

Abstract

Here we report on the influence of various gases on electrical properties of Pt-contacted α-Ga2O3 and α-Ga2O3/ϵ-Ga2O3 structures produced by halide vapor phase epitaxy on planar and patterned sapphire substrates. Pt-contacted α-Ga2O3 structures were highly resistive and exhibited no sensitivity to H2 and other gases. In contrast, α-Ga2O3/ϵ-Ga2O3 structures grown under the same conditions on patterned sapphire substrates exhibited clear and reversible response to H2. The response to H2 was thoroughly investigated at temperatures ranging from 25 °C to 200 °C and at applied biases from 1.5 V to 150 V. The lowest detectable limit of H2 at 125 °C was found to be 54 ppm. Selectivity of Ga2O3 structures against O2, NH3, СО, СН4, and H2O was examined at 125 °C and 200 °C. The structures showed little or no sensitivity to other gases at bias voltages below 7.5 V. Electrical and hydrogen sensing properties of these structures can be explained by a model of two back-to-back connected Schottky diodes which is widely used to describe metal-semiconductor-metal structures. Catalytically active Pt electrodes play an essential role in hydrogen sensing mechanism as they promote dissociation of hydrogen molecules. Accumulation of hydrogen atoms at Pt/ϵ-Ga2O3 interface results in the reduction of the Schottky energy barrier and current increase.

Preparation Properties and Device Application of ?- Ga2O3: A Review

“…When modeled LEDs were compared to planar LEDs, non-radiative recombination caused by high vector density becomes forward at a lower vector density. The sapphire substrate model for growing thin Ga 2 O 3 films can lower the energy barrier in LEDs, allowing more current to pass [83]. Zhou et al revealed that Ga 2 O 3 [84] based AlGaN UV LEDs with a specific resistance at contact about 2.36 ×10 3 cm 2 may achieve up to 93 % transmission at 365 nm.…”

Polymorphism and Faceting in Ga2O3 Layers Grown by HVPE at Various Gallium‐to‐Oxygen Ratios

“…Such α-Ga 2 O 3 /ε(κ)-Ga 2 O 3 structures grown by HVPE on PSS can be used in gas sensors. [13] In this article, we systematically investigated peculiarities of nucleation and luminescent properties of the Ga 2 O 3 layers grown by HVPE at different oxygen-to-gallium (VI/III ratio) ratios fluxes in a single process on PSS, GaN-on-sapphire templates, and m-plane sapphire substrates. We found that the threefold variation of VI/III ratio does not noticeably affect the luminescent intensity and spectra for all types of the substrates but changes distinguishably the growth rate for every kind of the layer.…”

Влияние влажности окружающей среды на электрическую проводимость полиморфных Ga-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=--структур

“…Фаза ε-Ga 2 O 3 интересна тем, что обладает спонтанной поляризацией [2]. Оба указанных политипа оксида галлия уже сейчас опробованы для ряда применений [1,11,[17][18][19][20] в области электронных приборов и сенсоров.…”

“…В своей предыдущей работе [20] мы показали возможность разработки селективных датчиков низких концентраций H 2 в диапазоне рабочих температур 25−200 • C на основе структур α-Ga 2 O 3 /ε-Ga 2 O 3 с платиновыми контактами. Ключевым фактором для проявления чувствительности структур к водороду (H 2 ) является использование каталитически активного металла -платины (Pt) -в качестве электрода.…”