Lyman spectra of holes bound to Cu, Ag, and Au acceptors in ZnTe and CdTe

TL;DR

This paper investigates the infrared absorption spectra of Cu, Ag, and Au impurities in ZnTe and CdTe, revealing their bound hole states and comparing experimental results with effective mass theory predictions.

Contribution

It provides detailed experimental analysis of Lyman spectra of group IB impurities in II-VI semiconductors and interprets complex features like phonon coupling and Fano asymmetries.

Findings

Bound hole states match effective mass theory predictions.

Observation of Fano-like asymmetries in spectra.

Identification of phonon-assisted excitation processes.

Abstract

The group IB impurities (Cu, Ag, and Au) incorporated into II-VI zinc blende hosts of ZnTe and CdTe exhibit well resolved excitation lines followed by a photoionization continuum in their infrared absorption spectra. They are associated with transitions from a "1s-like" ground state to various "p-like" excited state characteristic of a hole bound to a Coulomb center. Their spacing agree well with those predicted in the effective mass theory for single acceptors as expected for group IB elements substitutionally replacing the group IIB cations of the host. The occurrence of the simultaneous excitation of the Lyman transitions in combination with the zone center longitudinal optical phonon and hence lying in the photoionization continuum and displaying Fano-like asymmetries are features described and interpreted.