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【Domestic Papers】 Beijing University of Posts and Telecommunications —— Two-photon absorption induced photocurrent of a β-Ga₂O₃ film photodetector
日期：2025-03-13阅读：53
Researchers from the Beijing University of Posts and Telecommunications (BUPT) have published a dissertation titled "Two-photon absorption induced photocurrent of a β-Ga2O3 film photodetector" in Optics Express.
Abstract
The ultra-wide bandgap and diverse material systems of gallium oxide (Ga2O3) make it an attractive candidate for cutting-edge semiconductor research. In this work, two-photon absorption induced photocurrent generation in a β-Ga2O3 film photodetector was investigated using femtosecond laser pulses over a wide range of average incident powers and input laser wavelengths. The occurrence of two-photon absorption (TPA) in nonlinear photocurrent generation was confirmed by analyzing the power-dependent response in which the photocurrent of the β-Ga2O3 film photodetectors shows a quadratic dependence on incident power. The spectral response of the TPA photocurrent peaks around 200 nm, exhibiting a 50 nm blue shift compared to the one-photon response. This difference results from their distinct selection rules. The large blue shift into the ultraviolet (UV) spectral region is advantageous for measuring the pulse duration of ultrafast laser pulses in the UV region. Subsequently, we tentatively performed an autocorrelation measurement based on the TPA-induced photocurrent of the β-Ga2O3 film photodetectors at 400 nm. This approach shows potential for developing an autocorrelator to measure ultrafast laser pulses in the ultraviolet region of 370 to 440 nm, as indicated by the TPA photocurrent spectrum.
Fig. 1. (a). Schematic diagram of experimental TPA photocurrent measurement. NDF, neutral density filter; HWP, half-wave plate. (b). Measured TPA photocurrent responses of β-Ga2O3 film photodetector at two typical input wavelengths of 400 nm (black square) and 440 nm (red dot) as a function of input laser power. (c). One photon current response (black curve) and UV-visible absorption spectra (red curve) of β-Ga2O3 film. Inset in (c) shows the enlarged single photon current response (black curve) and UV-visible absorption spectra in the region 300-600 nm. (d). Measured TPA photocurrent of β-Ga2O3 film photodetector as a function of input laser polarization at the wavelength of 400 nm at a bias of 10 V.
Fig. 2. Two-photon current of the β-Ga2O3 film photodetector against biased voltage of 10 V at wavelengths of 380, 390, 400, 420, and 440 nm beams at an input power of 1.5 mW.
DOI：
doi.org/10.1364/OE.551941
