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Carrier behavior in the vicinity of pit defects in GaN characterized by ultraviolet light-assisted Kelvin probe force microscopy
摘要： Surface potentials in the vicinity of V-pits (cone bottom) and U-pits (blunt bottom) on epitaxial GaN surface have been systematically studied using ultraviolet (UV) light-assisted Kelvin probe force microscopy (KPFM). The band structure models are established to understand variation of the surface potentials at the pits and planar surface with and without UV light. The photo-generated carrier behavior at the pit defects is studied. According to the surface potential results, it can be deduced that the carrier distributions around the V- and U-pits are uneven. In dark, the electron concentration at the bottom of V-pit (30n0) and U-pit (15n0) are higher than that at planar surface (n0). Under UV light, for V-pit, the electron concentration at the cone bottom (4.93×1011n0) is lower than that at the surrounding planar surface (5.68×1013n0). For U-pit, the electron concentration at the blunt bottom is 1.35×1012n0, which is lower than that at the surrounding planar surface (6.13×1013n0). The non-equilibrium electron concentrations at different locations are calculated. Based on the non-equilibrium electron concentration, it can be concluded that the carrier recombination rate at pit defects is higher than that at planar surface.
关键词： pit defects,electron concentration,surface potential
更新于2025-09-23 15:23:52
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STUDY OF PROPERTIES OF LASER-INDUCED PLASMA CHANNELS FODMED BY FEMTOSECOND LASER RADIATION
摘要： Laser-induced plasma channels (LIPC) formed during the interaction of ultrashort laser pulses with argon are studied. LIPC characteristics are studied at various pressures.
关键词： laser-induced plasma channel,electron concentration,electron temperature,optical breakdown
更新于2025-09-19 17:13:59
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Near-Surface Plasma Formed by Dual-Pulse Laser Action at Two Wavelengths on Titanium in Air
摘要： Spectra and structures of near-surface plasma torches were studied experimentally by measuring the speci? c mass loss and plume luminosity caused by dual-pulse laser radiation at wavelengths 1064 and 532 nm on titanium in air as functions of the time between laser pulses and their sequence. Dependences of the laser-plasma temperature and concentration of charged particles on the paired laser pulse parameters were established at laser radiation power densities q1064 ≤ 3.1·109 and q532 ≤ 2.7·109 W/cm2 for λ = 1064 and 532 nm. The optimal conditions for recording erosion plasma spectra had the initial effect from second-harmonic radiation with a time interval between pulses of 4–5 μs; for speci? c mass loss, 3–6 μs. The results were important for enhancing the ef? ciency of laser emission spectral analysis and laser-plasma processing of materials.
关键词： speci? c mass loss,laser plasma,plasma-torch structure,plasma temperature,electron concentration,dual-pulse laser action
更新于2025-09-16 10:30:52