Novel Ohmic Contact Technology to P-type and N-type GaN

n型和p型GaN、AlGaN和GaInN的欧姆接触的比电阻对于许多器件特性（例如功率效率、放大、噪声、器件发热和可靠性）非常重要。在这项工作中，一个从根本上新颖的方法来低电阻欧姆接触AlGaN，GaInN和GaN将被开发和研究。接触是基于在GaN和相关化合物中发生的强自发和压电极化场的就业。金属-半导体接触近表面层中的极化场将提高载流子的隧穿几率，从而降低欧姆接触比电阻。有关隧穿概率，接触形成，和特定的接触电阻的理论和建模将被开发。极化增强的接触将被证明，降低接触电阻将被验证。此外，极化场在AlGaN-GaN超晶格中的作用将被研究，并且超晶格将被优化用于欧姆接触应用。 工作的一个组成部分将是在光电和电子器件中引入极化增强欧姆接触。发光二极管（LED），特别是用于高功率照明应用的LED，需要低电阻欧姆接触，以便减少器件发热并提高器件效率和可靠性。将展示具有极化增强欧姆接触的GaN/GaInN LED。偏振增强欧姆接触也将在激光器和晶体管中实现，并且这些器件的性能改进将得到证明。*

The specific resistance of ohmic contacts to n- and p-type GaN, AlGaN, and GaInN are very important for many device properties such as power efficiency, amplification, noise, device heating, and reliability. In this work, a fundamentally novel approach to low-resistance ohmic contacts to AlGaN, GaInN, and GaN will be developed and investigated. The contacts are based on the employment of the strong spontaneous and piezoelectric polarization fields occurring in GaN and related compounds. The polarization fields in the near-surface layers of metal-semiconductor contacts will enhance the tunneling probability of carriers thereby reducing the ohmic contact specific resistance. The theory and modeling pertaining to tunneling probability, contact formation, and specific contact resistance will be developed. Polarization-enhanced contacts will be demonstrated and reduced contact resistances will be verified. In addition, the role of polarization fields in AlGaN-GaN superlattices will be investigated and the superlattices will be optimized for ohmic contact applications. An integral part of the work will be the incorporation of the polarization-enhanced ohmic contacts in optoelectronic and electronic devices. Light-emitting diodes (LEDs), in particular LEDs used for high-power illumination applications, are in need of low resistance ohmic contacts in order to reduce device heating and improve device efficiency and reliability. GaN/GaInN LEDs with polarization-enhanced ohmic contacts will be demonstrated. Polarization-enhanced ohmic contacts will also be realized in lasers and transistors and improved properties of these devices will be demonstrated.******************************************************************