| Title |
Noise spectroscopy of heterostructures with a gallium oxide layer |
| Translation of Title |
Įvairialyčių darinių su galio oksido sluoksniu triukšminė spektroskopija. |
| Authors |
Gudeliauskas, Kipras |
| Full Text |
|
| Pages |
32 |
| Keywords [eng] |
Noise spectroscopy, Low-frequency noise, Voltage noise spectral density, β ; -Ga₂ ; O₃ ; , Gallium oxide heterostructures, Flicker noise, Generation-recombination noise, Lorentzian noise components, Trap centers, Etched Ga₂ ; O₃ ; structures, Surface and near-surface defects |
| Abstract [eng] |
In this work, the low-frequency noise characteristics of β-Ga₂O₃ semiconductor layers were investigated. The study analyzes the dependence of the voltage noise spectral density on frequency, voltage, and sample resistance. The voltage fluctuation spectral densities were measured over a wide temperature range of 77 K–293 K, using a low-noise amplifier and measuring in the frequency range of 10 Hz–20 kHz. At room temperature, 1/f and 1/f^α type noise dominated in the non-etched TO-E6 sample, with its intensity increasing as the voltage increased. As the sample resistance increased, a decrease in the noise level was observed. The voltage fluctuation spectral densities of the shorter 12 μm sample were two orders of magnitude higher than those of the 65 μm sample when the voltage across the sample was 2 V. In the etched TO-D2-06 sample, the noise level was significantly higher than in the non-etched sample. Etching depths of 20 nm and 30 nm in the gallium oxide structure increased the voltage fluctuation spectral density. The observed noise was of the 1/f and 1/f^α type. Simultaneous correlation measurements showed that the noise spectra of separate sample layers were not correlated (<2%), while the noise spectra of partially overlapping layers showed strong correlation (>80%). The absence of correlation between non-overlapping layers indicates that the current flowed only through the investigated gallium oxide layers. Lorentzian-type spectra were observed in the temperature-dependent measurements. By analyzing the temperature-dependent decrease of the voltage fluctuation spectral density, the spectra were modeled. After determining the relaxation times of the activation centers, their activation energies were calculated for two etched samples: for the 15 μm long sample with 20 nm etching, the energy was E ≈ 0.11 eV, while for the deeper 30 nm etched and 15 μm long sample, the energy was E ≈ 0.13 eV. The activation energies are low, therefore they are likely related to surface defects in the semiconductor structure. |
| Dissertation Institution |
Vilniaus universitetas. |
| Type |
Master thesis |
| Language |
English |
| Publication date |
2026 |
