Detecting the Photoexcited Carrier Distribution Across GaAs/Transition Metal Oxide Interfaces by Coherent Longitudinal Acoustic Phonons.
A prominent architecture for solar energy conversion layers diverse materials, such as traditional semiconductors (Si, III-V) and transition metal oxides (TMOs), into a monolithic device. The efficiency with which photoexcited carriers cross each layer is critical to device performance and dependent on the electronic properties of a heterojunction. Here, by time-resolved changes in the reflectivity after excitation of an n-GaAs/p-GaAs/TMO (Co3O4, IrO2) device, we detect a photoexcited carrier distribution specific to the p-GaAs/TMO interface through its coupling to phonons in both materials. The photoexcited carriers generate two coherent longitudinal acoustic phonons (CLAPs) traveling in opposite directions, one into the TMO and the other into the p-GaAs. This is the first time a CLAP is reported to originate at a semiconductor/TMO heterojunction. Therefore, these experiments seed future modeling of the built-in electric fields, the internal Fermi level, and the photoexcited carrier density of semiconductor/TMO interfaces within multilayered heterostructures.
Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States.
Kevin L
KL
Pollock
Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States.
Hoang Q
HQ
Doan
Department of Physics, University of Florida , Gainesville, Florida 32611, United States.
Avinash
A
Rustagi
Department of Physics, University of Florida , Gainesville, Florida 32611, United States.
Christopher J
CJ
Stanton
Department of Chemistry, University of California, Berkeley , Berkeley, California 94720, United States.|Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
Tanja
http://orcid.org/0000-0002-1635-2946
T
Cuk