Low Sheet Resistance GaN Channel on Si Substrates Using InAlN and AlGaN Bi-Layer Capping Stack

摘要

Transistors or transistor layers include an InAlN and AlGaN bi-layer capping stack on a 2DEG GaN channel, such as for GaN MOS structures on Si substrates. The GaN channel may be formed in a GaN buffer layer or stack, to compensate for the high crystal structure lattice size and coefficient of thermal expansion mismatch between GaN and Si. The bi-layer capping stack an upper InAlN layer on a lower AlGaN layer to induce charge polarization in the channel, compensate for poor composition uniformity (e.g., of Al), and compensate for rough surface morphology of the bottom surface of the InAlN material. It may lead to a sheet resistance between 250 and 350 ohms/sqr. It may also reduce bowing of the GaN on Si wafers during growth of the layer of InAlN material, and provide a AlGaN setback layer for etching the InAlN layer in the gate region.

主权项

1. A method to form transistor layers comprising:
forming a GaN channel layer of GaN material on a top surface of a substrate; forming a bi-layer capping stack on a top surface of the GaN channel layer, wherein forming the bi-layer capping stack includes:
forming a lower capping AlGaN layer of AlGaN material on a top surface of an AlN layer formed on the top surface of the GaN channel layer; andforming an upper capping AlInN layer of AlInN material on a top surface of the AlGaN material.