Semi-insulating silicon carbide without vanadium domination

• US 6,403,982 B2
• Filed: 01/10/2001
• Issued: 06/11/2002
• Est. Priority Date: 05/18/1999
• Status: Expired due to Term

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Brady, Mark, Tsvetkov, Valeri F., Carter, Calvin H. Jr.
• Primary Examiner(s): Clark, Sheila V.
• Application Number:
  US09/757,950
• Publication Number:
  US 20010019132A1
• Time in Patent Office: 517 Days
• Field of Search: 257/77, 257/78, 257/76
• US Class Current: 257/77
• CPC Class Codes: C30B 23/00 Single-crystal growth by condensing evaporated or sublimed materials
• CPC Class Codes: C30B 29/36 Carbides
• CPC Class Codes: C30B 33/00 After-treatment of single crystals or homogeneous polycrystalline material with defined structure C30B31/00 takes precedence

Abstract

A semi-insulating bulk single crystal of silicon carbide is disclosed that has a resistivity of at least 5000 Ω-cm at room temperature and a concentration of deep level trapping elements that is below the amounts that will affect the resistivity of the crystal, preferably below detectable levels. A method of forming the crystal is also disclosed, along with some resulting devices that take advantage of the microwave frequency capabilities of devices formed using substrates according to the invention.

Claims

1. A semi-insulating bulk single crystal of silicon carbide having a resistivity of at least 5000 Ω

-cm at room temperature, a concentration of deep level trapping elements that is below the amount that affects the electrical characteristics of the crystal, and a concentration of nitrogen atoms below 1×

10¹⁷ cm<sup>−

3</sup>.

2. A silicon carbide single crystal according to claim 1 wherein the polytype of the silicon carbide is selected from the group consisting of the 3C, 4H, 6H and 15R polytypes.

3. A silicon carbide single crystal according to claim 1 having a concentration of nitrogen atoms below 1×

10¹⁷ cm<sup>−

3</sup>.

4. A silicon carbide single crystal according to claim 1 wherein the concentration of nitrogen is 5×

10¹⁶ cm<sup>−

3</sup> or less.

5. A silicon carbide single crystal according to claim 1 wherein the concentration of deep level trapping elements is below the level that can be detected by secondary ion mass spectroscopy (SIMS).

6. A silicon-carbide single crystal according to claim 1 wherein the concentration of vanadium is below the level that can be detected by secondary ion mass spectroscopy (SIMS).

7. A silicon carbide single crystal according to claim 1 wherein the concentration of vanadium is less than 1×

10¹⁶ cm<sup>−

3</sup>.

8. A silicon carbide single crystal according to claim 1 wherein the concentration of vanadium is less than 1×

10¹⁴ cm<sup>−

3</sup>.

9. A silicon carbide single crystal according to claim 1 having a resistivity of at least 50,000 Ω

-cm at room temperature.

10. A transistor having a substrate that comprises the bulk single crystal according to claim 1.

11. A transistor according to claim 10 selected from the group consisting of:

metal-semiconductor field-effect transistors, metal-insulator field effect transistors, and high electron mobility transistors.

12. A semi-insulating bulk single crystal of silicon carbide having a resistivity of at least 5000 Ω

-cm at room temperature and a concentration of deep level trapping elements that is below the level that can be detected by secondary ion mass spectroscopy (SIMS).

13. A semi-insulating bulk single crystal of silicon carbide having a resistivity of at least 5000 Ω

-cm at room temperature and a concentration of vanadium that is less than 1×

10¹⁶ cm<sup>−

3</sup>.

14. A semi-insulating bulk single crystal of silicon carbide having a resistivity of at least 50000 Ω

-cm at room temperature and a concentration of deep level trapping elements that is below the amount that affects the electrical characteristics of the crystal.