Surface morphology of non-polar gallium nitride containing substrates
View Patent ↗Optical devices such as LEDs and lasers are discloses. The devices include a non-polar gallium nitride substrate member having an off-axis non-polar oriented crystalline surface plane. The off-axis non-polar oriented crystalline surface plane can be up to about −0.6 degrees in a c-plane direction and up to about −20 degrees in a c-plane direction in certain embodiments. In certain embodiments, a gallium nitride containing epitaxial layer is formed overlying the off-axis non-polar oriented crystalline surface plane. In certain embodiments, devices include a surface region overlying the gallium nitride epitaxial layer that is substantially free of hillocks.
1. An optical device comprising:
a gallium and nitrogen containing substrate member having an off-axis m-plane oriented crystalline surface plane, the off-axis m-plane oriented crystalline surface plane ranging from about +/−0.6 degrees to about +/−20 degrees toward a c-plane;
a gallium and nitrogen containing epitaxial layer formed overlying the off-axis m-plane oriented crystalline surface plane configured using at least a substantially atmospheric pressure epitaxial formation process to form at least a region of a quantum well having a thickness of at least 1.5 nanometers; and
a surface region overlying the gallium and nitrogen containing epitaxial layer, the surface region being substantially free from hillocks.
2. The device of claim 1 , wherein the gallium and nitrogen containing epitaxial layer comprises multiple layers, wherein the multiple layers comprise n-type regions, p-type regions, and/or multiple quantum wells.
3. The device of claim 1 , wherein the substantially atmospheric pressure ranges from about 650 Torr to 900 Torr.
4. The device of claim 1 , wherein the hillocks comprise one or more elongated hillocks oriented in an a-direction.
5. The device of claim 1 , wherein the hillocks comprise one or more pyramidal-like hillocks.
6. The device of claim 1 , wherein the gallium and nitrogen containing epitaxial layer comprises a surface region that is substantially free from hillocks.
7. The device of claim 1 , wherein the gallium and nitrogen containing epitaxial layer comprises a surface region that is substantially free from hillocks having a length ranging from 10 microns to 100 microns.
8. The device of claim 1 , wherein the gallium and nitrogen containing epitaxial layer comprises the surface region that is substantially free from hillocks having a length ranging from 100 microns to 200 microns.
9. The device of claim 1 , wherein the gallium and nitrogen containing epitaxial layer comprises a surface region, wherein at least 90% of the surface region is free from hillocks.
10. The method of claim 1 , wherein the epitaxial layer is formed using a pure nitrogen entity carrier gas.
11. The device of claim 1 , wherein the off-axis m-plane oriented crystalline surface plane is greater in magnitude than about 1 degree toward (0001).
12. The device of claim 1 wherein the off-axis m-plane oriented crystalline surface plane is greater in magnitude than about 3 degrees toward (0001).
13. The device of claim 1 wherein the off-axis m-plane oriented crystalline surface plane is greater in magnitude than about 5 degrees toward (0001).
14. The device of claim 1 wherein the off-axis m-plane oriented crystalline surface plane is greater in magnitude than about 10 degrees toward (0001).
15. The device of claim 1 wherein the off-axis m-plane oriented crystalline surface plane is greater in magnitude than about 15 degrees toward (0001).
16. The device of claim 1 , wherein the off-axis m-plane oriented crystalline surface plane is characterized by a semipolar plane selected from the (30-31) plane, the (30-3-1) plane, the (20-21) plane, the (20-2-1) plane, the (30-32) plane, and the (30-3-2) plane.
17. The device of claim 1 , wherein the optical device is an LED device configured to operate in the blue wavelength regime from 430 nm to 480 nm or in the green wavelength regime from 500 nm to 550 nm.
18. The device of claim 1 , wherein the optical device is a laser diode device configured to operate in the blue wavelength regime from 430 nm to 480 nm or in the green wavelength regime from 500 nm to 550 nm.