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

欧姆触点对n型和p型GaN、AlGaN和GaInN的比电阻对许多器件性能（如功率效率、放大、噪声、器件加热和可靠性）非常重要。在这项工作中，将开发和研究一种全新的低阻欧姆接触AlGaN， GaInN和GaN的方法。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使用。金属-半导体触点近表面的极化场会提高载流子的隧穿概率，从而降低接触的欧姆比电阻。理论和模型有关隧道的可能性，接触形成，和比接触电阻将发展。将演示极化增强触点，并验证触点电阻的降低。此外，还将研究极化场在AlGaN-GaN超晶格中的作用，并针对欧姆接触应用对超晶格进行优化。这项工作的一个组成部分将是光电和电子器件中极化增强欧姆接触的结合。发光二极管（led），特别是用于大功率照明应用的led，需要低电阻欧姆接触，以减少器件发热，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。Polarization-enhanced欧姆接触也将实现激光和晶体管和提高这些设备的属性将会证明 .******************************************************************

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.******************************************************************