Use of surfactants to control island size and density
Methods of controlling island size and density on an OMVPE growth film may comprise adding a surfactant at a critical concentration level, allowing a growth phase for a first period of time, and ending the growth phase when desired island size and density are achieved. For example, the island size and density of an OMVPE grown InGaN thin film may be controlled by adding an antimony surfactant at a critical concentration level.
1. A method of incorporating indium onto a growth film at an elevated growth temperature comprising:
providing a growth film;
depositing a buffer layer on the growth film;
placing the growth film in an organometallic vapor phase epitaxy (OMVPE) growth environment having an elevated growth temperature;
flowing a vapor comprising gallium and indium into the growth environment;
adding antimony (Sb) at least at or above a critical concentration level into the vapor; and
allowing the vapor to flow to maintain a growth phase for a period of time;
wherein after said growth phase and said period of time an indium incorporation fraction is at least 0.20 on a resultant growth film; and wherein adding the antimony at least at or above the critical concentration level results in an abrupt change in bandgap energy.
2. The method of claim 1 , wherein the growth film comprises a sapphire wafer.
3. The method of claim 1 , wherein the buffer layer comprises gallium nitride (GaN).
4. The method of claim 1 , wherein the elevated growth temperature is at least 720° C.
5. The method of claim 1 , wherein the In/(In+Ga) ratio is about 0.64.
6. The method of claim 1 , wherein a growth rate of the growth phase is 0.39 Å/s.
7. The method of claim 1 , wherein the critical concentration level of the Sb in the vapor ranges from greater than 1% to less than 1.25%.
8. The method of claim 7 , wherein the resultant growth film exhibits a bandgap energy of about 2.7 eV.
9. The method of claim 7 , wherein the resultant growth film exhibits an indium concentration of at least about 31%.
10. The method of claim 1 , wherein an indium incorporation fraction on the growth film is at least 0.25.
11. The method of claim 1 , wherein an indium incorporation fraction on the growth film is at least 0.29.
12. The method of claim 1 , wherein a surface of the resultant growth film comprises Stranski-Krastinov islands having an island size and density and wherein the island size and density exhibit an abrupt morphology change over a surface of a second resultant growth film comprising Stranski-Krastinov islands having a second island size and density which are grown under substantially the same conditions except at an Sb concentration below the critical concentration level.
13. The method of claim 1 , wherein the resultant growth film exhibits a PL emission spectra that differs from the PL emission spectra of a second resultant growth film grown under substantially the same conditions except an Sb concentration below the critical concentration level.
14. The method of claim 1 , wherein the critical concentration level of the Sb in the vapor is greater than 1%.
15. A method of making an indium gallium nitride film comprising:
providing a sapphire wafer;
depositing a gallium nitride (GaN) layer on the sapphire waffer;
placing the sapphire wafer in an organometallic vapor phase epitaxy (OMVPE) growth environment having temperature of at least 720° C.;
flowing a vapor comprising gallium and indium into the growth environment;
adding antimony (Sb) at least at or above a critical concentration level into the vapor; and
allowing the vapor to flow for a growth phase for a period of time;
wherein after said growth phase and said period of time an indium incorporation fraction is at least 0.20 on a resultant indium gallium nitride film; and wherein adding the antimony at least at or above the critical concentration level results in an abrupt change in bandgap energy.
16. The method of claim 15 , wherein the critical concentration level of the Sb ranges from greater than 1% to less than 1.25%.
17. The method of claim 15 , wherein the critical concentration level of the Sb is greater than 1%.