TY - JOUR
T1 - Impact of Extended Defects on Recombination in CdTe Heterostructures Grown by Molecular Beam Epitaxy
AU - Zaunbrecher, Katherine
AU - Kuciauskas, Darius
AU - Dippo, Patricia
AU - Barnes, Teresa
AU - Swartz, Craig
AU - Edirisooriya, Madhavie
AU - Ogedengbe, Olanrewaju
AU - Sohal, Sandeep
AU - Hancock, Bobby
AU - LeBlanc, Elizabeth
AU - Jayathilaka, Pathiraja
AU - Myers, Thomas
N1 - Publisher Copyright:
© 2016 Author(s).
PY - 2016/8/29
Y1 - 2016/8/29
N2 - Heterostructures with CdTe and CdTe1-xSex (x ∼ 0.01) absorbers between two wider-band-gap Cd1-xMgxTe barriers (x ∼ 0.25-0.3) were grown by molecular beam epitaxy to study carrier generation and recombination in bulk materials with passivated interfaces. Using a combination of confocal photoluminescence (PL), time-resolved PL, and low-temperature PL emission spectroscopy, two extended defect types were identified and the impact of these defects on charge-carrier recombination was analyzed. The dominant defects identified by confocal PL were dislocations in samples grown on (211)B CdTe substrates and crystallographic twinning-related defects in samples on (100)-oriented InSb substrates. Low-temperature PL shows that twin-related defects have a zero-phonon energy of 1.460 eV and a Huang-Rhys factor of 1.50, while dislocation-dominated samples have a 1.473-eV zero-phonon energy and a Huang-Rhys factor of 1.22. The charge carrier diffusion length near both types of defects is ∼6 μm, suggesting that recombination is limited by diffusion dynamics. For heterostructures with a low concentration of extended defects, the bulk lifetime was determined to be 2.2 μs with an interface recombination velocity of 160 cm/s and an estimated radiative lifetime of 91 μs.
AB - Heterostructures with CdTe and CdTe1-xSex (x ∼ 0.01) absorbers between two wider-band-gap Cd1-xMgxTe barriers (x ∼ 0.25-0.3) were grown by molecular beam epitaxy to study carrier generation and recombination in bulk materials with passivated interfaces. Using a combination of confocal photoluminescence (PL), time-resolved PL, and low-temperature PL emission spectroscopy, two extended defect types were identified and the impact of these defects on charge-carrier recombination was analyzed. The dominant defects identified by confocal PL were dislocations in samples grown on (211)B CdTe substrates and crystallographic twinning-related defects in samples on (100)-oriented InSb substrates. Low-temperature PL shows that twin-related defects have a zero-phonon energy of 1.460 eV and a Huang-Rhys factor of 1.50, while dislocation-dominated samples have a 1.473-eV zero-phonon energy and a Huang-Rhys factor of 1.22. The charge carrier diffusion length near both types of defects is ∼6 μm, suggesting that recombination is limited by diffusion dynamics. For heterostructures with a low concentration of extended defects, the bulk lifetime was determined to be 2.2 μs with an interface recombination velocity of 160 cm/s and an estimated radiative lifetime of 91 μs.
KW - diffusion
KW - epitaxy
KW - II-VI semiconductors
KW - III-V semiconductors
KW - photoluminescence
UR - http://www.scopus.com/inward/record.url?scp=84985036676&partnerID=8YFLogxK
U2 - 10.1063/1.4961989
DO - 10.1063/1.4961989
M3 - Article
AN - SCOPUS:84985036676
SN - 0003-6951
VL - 109
SP - 19446
EP - 19455
JO - Applied Physics Letters
JF - Applied Physics Letters
IS - 9
M1 - Article No. 091904
ER -