Method of fabricating ohmic contact on n-type gallium nitride (GaN) of room temperature by plasma surface treatment
View Patent ↗Forming low contract resistance metal contacts on GaN films by treating a GaN surface using a chlorine gas Inductively Coupled Plasma (ICP) etch process before the metal contacts are formed. Beneficially, the GaN is n-type and doped with Si, while the metal contacts include alternating layers of Ti and Al. Additionally, the GaN film is dipped in a solution of HCl:H 2 O prior to metal contact formation.
1. A method of forming a metal contact on a GaN layer, comprising:
obtaining an n-type GaN substrate;
performing a Cl 2 plasma surface treatment using an inductively-coupled plasma (ICP) method on the entire surface of the GaN substrate; and
forming a metal contact on the plasma treated surface of the GaN substrate, wherein the metal contact forms an ohmic contact with the n-type GaN substrate.
2. The method of forming a metal contact according to claim 1 , wherein the metal contact includes Ti.
3. The method of forming a metal contact according to claim 1 , wherein the metal contact includes Al.
4. The method of forming a metal contact according to claim 1 , wherein the Cl 2 plasma treatment is performed at a base pressure of about 5×10 −5 Torr and at a flow rate of about 10 sccm of Cl 2 .
5. A method of forming a metal contact on a semiconductor, comprising:
growing an undoped GaN film on a sapphire substrate;
forming an n-type GaN film on the undoped GaN film;
performing a Cl 2 plasma surface treatment using an inductively-coupled plasma (ICP) method on the entire surface of the n-type GaN film; and
forming a metallic contact on the plasma treated surface of the n-type GaN film, wherein the metallic contact forms an ohmic contact with the n-type GaN film without any further treatment after the formation of the metal contact.
6. The method of forming a metal contact according to claim 5 , wherein the metal contact includes Ti.
7. The method of forming a metal contact according to claim 5 , wherein the metal contact includes Al.
8. The method of forming a metal contact according to claim 5 , wherein the undoped GaN film is grown by metal-organic chemical vapor deposition.
9. The method of forming a metal contact according to claim 5 , wherein the undoped GaN film has a thickness of about 1 μm.
10. The method of forming a metal contact according to claim 5 , wherein the n-type GaN film is doped with Si.
11. The method of forming a metal contact according to claim 5 , wherein the n-type GaN film is treated with HCl:H 2 O (1:1) before the metal contact is formed.
12. A method of producing a metal contact on a semiconductor, comprising:
forming an n-type GaN film on a substrate;
performing a Cl 2 plasma treatment using an inductively-coupled plasma (ICP) method on the entire surface of the n-type GaN film; treating the surface of the n-type GaN film with HCl:H 2 O after performing the Cl 2 plasma treatment; and
forming a metallic pad on the surface of the GaN film treated with HCl:H 2 O, wherein the metal pad forms an ohmic contact with the n-type GaN film.
13. The method of forming a metal contact according to claim 12 , wherein the metal contact includes Ti.
14. The method of forming a metal contact according to claim 13 , wherein the metal contact includes Al.
15. The method of forming a metal contact according to claim 14 , wherein the formed metal contact includes alternating layers of Ti and Al.
16. The method of forming a metal contact according to claim 15 , wherein the alternating layers of Ti and Al are formed using an electron beam evaporator.
17. The method of forming a metal contact according to claim 12 , wherein the n-type GaN film is doped with Si.
18. The method of forming a metal contact according to claim 12 , wherein the n-type GaN film is dipped in an HCl:H 2 O (1:1) solution.
19. A method of forming a metal contact on a GaN layer, comprising:
obtaining an n-type GaN substrate;
performing a Cl 2 plasma surface etching on the GaN substrate with same thickness through the entire surface treatment using an inductively-coupled plasma (ICP) method on the surface of the GaN substrate; and
forming a metal contact on the plasma treated surface of the GaN substrate, wherein the metal contact forms an ohmic contact with the n-type GaN substrate.