Method of forming lateral pn junctions in III-nitrides using p-type and n-type co-doping and selective p-type activation and deactivation
Methods are provided of selectively obtaining n-type and p-type regions from the same III-Nitride layer deposited on a substrate without using diffusion or ion-implantation techniques. The III-Nitride layer is co-doped simultaneously with n-type and p-type dopants, with p-type dopant concentration higher than n-type dopant to generate p-n junctions. The methods rely on obtaining activated p-type dopants only in selected regions to generate p-type layers, whereas the rest of the regions effectively behave as an n-type layer by having deactivated p-type dopant atoms.
1. A semiconductor structure comprising:
a first region doped with a p-type dopant, an n-type dopant, and a passivating species, such that the passivating species deactivates an acceptor, and an active p-type dopant concentration is less than an active donor concentration (N D ), thus creating a n-type layer;
a second region adjacent the first region, wherein the second region is doped with the p-type dopant, the n-type dopant, and wherein the concentration of the passivating species is lower than the first region so that a p-type dopant concentration is higher than the active donor concentration (N D ), thus creating a p-type layer; and
an overlayer over the first region and the second region, wherein the overlayer is an out diffusion barrier for the passivating species.
2. The semiconductor structure of claim 1 , wherein the p-type dopant is Mg, the n-type dopant is Si or Ge, and the passivating species is H, and wherein the semiconductor structure is a III-Nitride semiconductor layer structure.
3. A method for fabricating a semiconductor structure comprising: The
depositing an overlayer on a sample surface of the semiconductor structure which acts as an out-diffusion barrier for a passivating species;
patterning the sample surface to retain the deposited overlayer in selected areas of the sample surface; and
performing activation treatment of the sample surface to obtain p-regions in areas without the overlayer and n-type regions in areas of the sample surface underneath the overlayer.
4. The method of claim 3 , wherein the overlayer comprises a dielectric or any material layer which act as out-diffusion barrier for the passivating species and prevents activation of layers below the sample surface.
5. The method of claim 3 , wherein patterning the sample surface comprises photolithography and subsequent etching process or selective regrowth.
6. The method of claim 3 , wherein subjecting the sample surface to a p-type activating process such as heating in nitrogen, oxygen or mixture of both gas flow which enables activation of Mg atoms in a III-Nitride material.
7. The method of claim 3 , wherein the method further comprises generating a lateral p-n junction configured for use with a lateral p-n diode, a lateral and vertical MOSFET, or a guard ring structure for vertical power devices.
8. A method for fabricating a semiconductor structure comprising:
depositing an overlayer on a sample surface of a semiconductor surface which acts as in-diffusion barrier to a passivating species;
patterning the sample surface to retain the deposited overlayer in selected areas of the sample surface; and
subjecting the sample surface to p-type deactivation treatment to obtain n-regions in areas without the overlayer and p-type regions in areas of the sample surface underneath the overlayer.
9. The method of claim 8 , wherein the overlayer comprises a dielectric or any material layer which act as in-diffusion barrier for the passivating species and prevents deactivation of layers below the sample surface.
10. The method of claim 8 , wherein patterning the sample surface could be done by any photolithography and subsequent etching process or selective regrowth.
11. The method of claim 8 , wherein subjecting the sample surface to a p-type deactivating process such as plasma exposer having the passivating species or treatment with any passivating species containing gas flow or any other elements enables deactivation of Mg atoms in a III-Nitride material.
12. The method of claim 8 , wherein the method further comprises heating or cooling the sample surface to enable efficient and deeper deactivation process.
13. The method of claim 8 , wherein the method further comprises generating a lateral p-n junction configured for use with a lateral p-n diode, a lateral and vertical MOSFET, or a guard ring structure for vertical power devices.