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 cy clotron resonance plasmas which have been used in the depositions of GaN fi lms on the substrate of (0001) alpha-Al2O3. These plasmas were generated wi th 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 t he plasma parameter, such as ion density(N-i), electron temperature(T-e), p lasma 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 G aN film strongly depend on the growth condition. The higher the plasma dens ity, the higher the N/Ga ratio of GaN film. When the microwave power was 85 0 W and gas pressure was 0.22 Pa, the plasma near the substrate was charact erized by a T-e near 1.4 eV and plasma density near 2.0 x 10(11) cm(-3), an d 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.