Hole-Doping to a Cu(I)-Based Semiconductor with an Isovalent Cation: Utilizing a Complex Defect as a Shallow Acceptor

Area of Science:

• Materials Science
• Solid State Physics
• Semiconductor Physics

Background:

• p-Type doping in copper(I)-based semiconductors is essential for improving solar cell performance.
• Impurity doping is key to overcoming intrinsic limitations in hole concentration set by native defects.

Purpose of the Study:

• To investigate alkali metal impurities as p-type dopants in Cu(I)-based cation-deficient semiconductors.
• To demonstrate enhanced hole concentration controllability using cesium (Cs) impurity in gamma-copper(I) iodide (γ-CuI).

Main Methods:

• Experimental synthesis and characterization of doped γ-CuI single crystals and thin films.
• First-principles calculations to understand impurity behavior and defect complex formation.

Main Results:

• Isovalent alkali metal impurities, particularly Cs, preferentially occupy interstitial sites in γ-CuI due to size mismatch.
• Cesium impurity doping enables precise control of hole concentration from 10^13 to 10^19 cm^-3.
• First-principles calculations confirm Cs forms shallow acceptor impurity-defect complexes, boosting p-type conductivity.

Conclusions:

• Isovalent doping with alkali metals offers a novel strategy for controlled p-type doping in cation-deficient semiconductors.
• The interaction between impurities and native defects is crucial for achieving enhanced doping effects.
• This approach advances the development of efficient materials for solar cells and other electronic devices.