Defect Compensation in Nitrogen-Doped β-Ga₂O₃ Nanowires: Implications for Bipolar Nanoscale Devices

Abstract

Nitrogen (N) is a promising candidate currently being pursued for p-type doping in Ga2O3. In this work, the results of detailed investigations into N-doped β-Ga2O3 nanowires using microstructural, chemical, and optical analyses are described. Monoclinic β-Ga2O3 nanowires are grown by chemical vapor deposition using a metallic gallium (Ga) precursor and subsequently doped with N by remote plasma by exploiting their nanoscale cross sections and large surface-to-volume ratios. The N incorporation into β-Ga2O3 is confirmed by X-ray absorption near-edge and Raman spectroscopies without changes in the nanowire morphology. N is found to exist mainly as molecular N2 and N–O chemical states, but a significant portion of N substitutes on oxygen (O) sites. Concurrent temperature-resolved cathodoluminescence measurements of the undoped and N-doped β-Ga2O3 are used to track the temperature dependences of their intrinsic ultraviolet (UV) luminescence and defect-related visible bands from 80 to 480 K. The blue and green bands increase in intensity relative to the UV after N doping; however, their intensity variations with temperature are found to be identical for the undoped and N-doped β-Ga2O3, indicating that these bands originate from existing recombination pathways in Ga2O3 rather than from radiative N-related centers. The enhancement in defect-related luminescence in N-doped β-Ga2O3 is explained by an increase in the concentration of O vacancies as a result of the compensation of NO acceptors.

Observation of Anomalous Negative Photoconductivity in Ga2O3 Nanowires: Implications for Broadening the Spectral Response of Photodetectors

“…However, the formation energies of oxygen vacancies are much lower than that of interstitial Ga, so the donor electrons are mainly offered by oxygen vacancies. The acceptors may originate from Ga vacancies (V Ga 2– ) or gallium–oxygen vacancy pairs ((V Ga + V o ) 1– ). ,− According to the previous reports, the appearance of green bands may also be a result of DAP recombination, , which is due to the recombination of electrons trapped by oxygen vacancies and holes captured by neutral oxygen interstitial defects (O i ) with a slight contribution of V Ga 2– . , The transition processes mentioned above are visualized in the inset of Figure a.…”

High-Speed and Ultrasensitive Solar-Blind Ultraviolet Photodetectors Based on In Situ Grown β-Ga2O3 Single-Crystal Films

“…The BL and UVL bands have been widely reported in Ga 2 O 3 thin films, in which the BL band (2.9 eV, 430 nm) is attributed to V o or the ( V o , V Ga ) vacancy pair. In addition, the UVL band can be further divided into two components. , Wang et al reported that the UVL bands at 3.4 eV (350 nm) and UV′L at 3.1 eV (400 nm) were caused by the STHs and V o , respectively . Therefore, the Ga 2 O 3 spectra were fitted by the Gaussian peak, which can be deconvoluted into UVL, UV′L, and BL components with the positions of E UV = 3.40 ± 0.05 eV, E UV′ = 3.10 ± 0.05 eV, and E B = 2.90 ± 0.05 eV, respectively. , The results show that the intensity of the UVL band decreases significantly, while that of UV′L and BL changes weakly, as shown in Figure a–d.…”

Enhancement of crystalline quality and solar-blind photodetection characteristics of ε-Ga2O3 films by introducing Zn impurity

“…Owing to the similar ionic radii of Ga 3+ (0.062 nm) and Zn 2+ (0.074 nm), Zn alloying/doping has been widely used to improve the performance of Ga 2 O 3 , [31][32][33][34][35] and some results show that the oxygen vacancy defects can be significantly suppressed by introducing Zn into Ga 2 O 3 . 36,37 However, most previously studies have focused on the most stable b-Ga 2 O 3 , while relatively few studies have been conducted on other metastable phases; 38,39 in particular, Zn-doped e-Ga 2 O 3 has still not been reported.…”