Properties of electron cyclotron resonance plasmas and their influence on the deposition of GaN films

Langmuir probes and Faraday cups have been used to characterize electron cyclotron resonance plasmas which have been used in the depositions of GaN films on the substrate of (0001) alpha-Al2O3. These plasmas were generated with microwave power (P-w) from 300 W to 1100 W at pressures (p) range from 0.8 Pa to 0.05 Pa using N-2 as the plasma source. The relationship between the plasma parameter, such as ion density(N-i), electron temperature(T-e), plasma potential(V-p) and ion current density(J(i)), and system parameters, such as p(W) and p, is given. And the axial and radial distributions of T-e, N-i, V-p and J(i) are presented. The growth rate and the quality of the GaN film strongly depend on the growth condition. The higher the plasma density, the higher the N/Ga ratio of GaN film. When the microwave power was 850 W and gas pressure was 0.22 Pa, the plasma near the substrate was characterized by a T-e near 1.4 eV and plasma density near 2.0 x 10(11) cm(-3), and the growth-rate of GaN was as high as 0.9 mu m/h. The full width at half maximum of double-crystal X-ray diffraction rocking curve is 16 arcmin.