Radiative Recombination Dominated Monocrystalline CdTe/MgCdTe Double-Heterostructures

Monocrystalline CdTe/MgCdTe double-heterostructures (DHs) grown on lattice-matched InSb substrates have achieved remarkable carrier-lifetimes up to 3.6 μs recently. In this paper, external luminescence quantum efficiencies η
_ext
of CdTe/MgCdTe DHs are determined using photoluminescence quantum efficiency measurements. The external luminescence quantum efficiency of a 1-μm-thick CdTe/MgCdTe DH with indium-doped n-type at 1 × 10
¹⁷
cm
^-3
is measured to be 3.0% under one-sun condition, i.e., a carrier injection current density of ~30 mA/cm
²
, which corresponds to a spontaneous emission quantum efficiency η
_q
of 90 ± 4%. Such a high efficiency gives an implied open-circuit voltage V
_oc
, or quasi-Fermi-level splitting of 1.13 V. The η
_q
of unintentionally doped DH samples with optimum barrier layers can be over 95% at one-sun injection level.