Methods of forming zinc oxide based II-VI compound semiconductor layers with shallow acceptor conductivities

• US 7,723,154 B1
• Filed: 10/19/2006
• Issued: 05/25/2010
• Est. Priority Date: 10/19/2005
• Status: Expired due to Fees

• Current Assignee: LumenZ, Inc, North Carolina State University (University of North Carolina System)
• Original Assignee: LumenZ, Inc, North Carolina State University (University of North Carolina System)
• Inventors: Kenney, George B., Adekore, Bunmi T., Davis, Robert F., Pierce, Jonathan M.
• Primary Examiner(s): SMITH, BRADLEY
• Application Number:
  US11/551,058
• Time in Patent Office: 1,314 Days
• Field of Search: 438/104
• US Class Current: 438/104
• CPC Class Codes: H01L 21/0237 Materials
• CPC Class Codes: H01L 21/02554 Oxides
• CPC Class Codes: H01L 21/02565 Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
• CPC Class Codes: H01L 21/02573 Conductivity type
• CPC Class Codes: H01L 21/02579 P-type
• CPC Class Codes: H01L 21/02581 Transition metal or rare earth elements
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 21/425 producing ion implantation

Abstract

A p-type ZnO-based II-VI compound semiconductor layer has silver, potassium and/or gold dopants therein at a net p-type dopant concentration of greater than about 1×10¹⁷ cm⁻³. A method of forming the layer includes using an atomic layer deposition (ALD) technique. This technique includes exposing a substrate to a combination of gases: a first reaction gas containing zinc at a concentration that is repeatedly transitioned between at least two concentration levels during a processing time interval, a second reaction gas containing oxygen and a p-type dopant gas containing at least one p-type dopant species selected from a group consisting of silver, potassium and gold. A concentration of oxygen in the second reaction gas may also be repeatedly transitioned between at least two concentration levels. The concentration of zinc in the first reaction gas and the concentration of oxygen in the second reaction gas may be transitioned in an alternating sequence, so that relatively high zinc concentrations in the first reaction gas overlap with relatively low oxygen concentrations in the second reaction gas and vice versa.

Claims

1. A method of forming a p-type ZnO-based II-VI compound semiconductor layer, comprising:

incorporating sufficient quantities of silver, potassium and/or gold dopants into a zinc sublattice within a ZnO-based II-VI compound semiconductor layer under processing conditions that yield a net p-type dopant concentration therein, said incorporating comprising forming a ZnO-based II-VI compound semiconductor layer using an atomic layer deposition technique.

2. The method of claim 1, wherein said incorporating comprises incorporating sufficient quantities of silver, potassium and/or gold dopants into a zinc sublattice within a ZnO-based II-VI compound semiconductor layer under processing conditions that yield a net p-type dopant concentration of greater than about 1×

10¹⁷ cm<sup>−

3</sup> therein for dopants having an acceptor ionization energy below about 355 meV.

3. The method of claim 1, wherein the p-type ZnO-based II-VI compound semiconductor layer is selected from a group consisting of ZnO, ZnMgO, ZnCaO, ZnBeO, ZnSrO, ZnBaO, ZnCdO and ZnInO and MgCdZnO layers and composites of these layers.

4. The method of claim 1, wherein said incorporating comprises:

implanting the silver, potassium and/or gold dopants into the ZnO-based compound semiconductor layer; and

then

annealing the ZnO-based II-VI compound semiconductor layer at one or more temperatures in a range from about 250°

C. to about 2000°

C.

5. The method of claim 4, wherein said annealing step comprises exposing the ZnO-based II-VI compound semiconductor layer to an ambient in a range from about 25 mbar to about 7 kbar.

6. The method of claim 4, wherein said annealing step comprises exposing the ZnO-based II-VI compound semiconductor layer to a chemically inert ambient in a range from about 25 mbar to about 7 kbar.

7. The method of claim 4, wherein said implanting step comprises implanting the silver, potassium and/or gold dopants at multiple energy levels.

8. The method of claim 1, wherein said incorporating comprises incorporating sufficient quantities of the silver, potassium and/or gold dopants into the zinc sublattice under processing conditions that yield an activation level of greater than about 5% for the dopants.

9. The method of claim 1, wherein said incorporating comprises incorporating sufficient quantities of the silver, potassium and/or gold dopants into the zinc sublattice under processing conditions that yield an activation level of greater than about 10% for the dopants.

10. A method of forming a p-type semiconductor region, comprising:

forming a ZnO-based II-VI compound semiconductor region using an atomic layer deposition (ALD) technique; and

incorporating sufficient quantities of silver, potassium and/or gold dopants into the ZnO-based II-VI compound semiconductor region under processing conditions that yield a net p-type dopant concentration therein.

11. The method of claim 10, wherein said incorporating comprises incorporating sufficient quantities of silver, potassium and/or gold dopants into the ZnO-based II-VI compound semiconductor region under processing conditions that yield an activation level of greater than about 10% for the dopants.