Non-polar a-plane gallium nitride thin films grown by metalorganic chemical vapor deposition

#The invention is related to semiconductor materials, methods, and devices, and more particularly, to non-polar a-plane gallium nitride (GaN) thin films grown by metalorganic chemical vapor deposition (MOCVD).

#(Note: This application references a number of different patents, applications and/or publications as indicated throughout the specification by one or more reference numbers. A list of these different publications ordered according to these reference numbers can be found below in the section entitled “References.” Each of these publications is incorporated by reference herein.)

#Polarization in wurtzite III-nitride compounds has attracted increased attention due to the large effect polarization-induced electric fields have on heterostructures commonly employed in nitride-based optoelectronic and electronic devices. Nitride-based optoelectronic and electronic devices are subject to polarization-induced effects because they employ nitride films grown in the polar c-direction [0001], the axis along which the spontaneous and piezoelectric polarization of nitride films are aligned. Since the total polarization of a nitride film depends on the composition and strain state, discontinuities exist at interfaces between adjacent device layers and are associated with fixed sheet charges that give rise to internal electric fields.

#Referring now to the drawings in which like reference numbers represent corresponding parts throughout:

#FIG. 1 is a flowchart that illustrates the steps of the MOCVD process for the growth of non-polar (11{overscore (2)}0) a-plane GaN thin films on (1{overscore (1)}20) r-plane sapphire, according to the preferred embodiment of the present invention;

#FIG. 2(a) shows a 2θ-ω diffraction scan that identifies the growth direction of the GaN film as (1{overscore (1)}20) a-plane GaN;

#In the following description of the preferred embodiment, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration a specific embodiment in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.

#Overview

#The present invention describes a method for growing device quality non-polar (11{overscore (2)}0) a-plane GaN thin films via MOCVD on (1{overscore (1)}02) r-plane sapphire substrates. The method employs a low-temperature buffer layer grown at atmospheric pressure to initiate the GaN growth on r-plane sapphire. Thereafter, a high temperature growth step is performed at low pressures, e.g., ˜0.1 atmospheres (atm) in order to produce a planar film.