Conclusion

Among III-V semiconductors, the gallium nitride sector took off in the 1990s. With improvements in material growth and crystalline quality, it is ideally suited to the production of power devices requiring high operating voltages, thanks to the large breakdown field associated with the large gap. The significant conduction band discontinuity at the AlGaN/GaN or AlInN/GaN heterojunction, and the high electron saturation rate in these materials, are also an asset for power applications, thanks to the high currents involved. The specificity of these materials is the presence of high spontaneous and piezoelectric polarizations, making doping of the barrier zone unnecessary. The most widely used substrates are SiC, thanks to its low lattice mismatch with GaN and excellent thermal conductivity, and highly resistive Si, available in larger surface areas and at lower cost. The GaN substrate, which...