Electrical Properties Of GaN Layers Grown By Metal Organic Vapor Phase Epitaxy (MOVPE)

The electrical properties of three un‐doped GaN samples grown at low pressure by Metal Organic Vapor Phase Epitaxy (MOVPE) on sapphire substrates are reported. Two different growth temperatures of $900 °C$ and $950 °C$ were used, for 90 min. Also, two trimethylgallium flow fluxes were set (5.39 μmole/minute and 8.39 μmole/minute). The temperature dependent Hall (T‐Hall) technique was used, between 35 K and 373 K. The resistivity of our samples fluctuated between 3 and $24 mΩ×cm.$ They were temperature dependent and were explained by two thermally activated processes, with activation energies of 20 and 70 meV. For the two samples grown at $900 °C,$ the mobilities and the charge carrier densities were temperature independent with values of 10 and $20 cm2 V−1 s−1,$ and $6×1019$ and $5×1019 cm−3,$ respectively. For the sample grown at $950 °C,$ the mobility showed temperature dependence to the power of $+1/3$ and the charge carrier density a thermally activated dependence with an activation energy of 5 meV.