12.3 Energy Levels in Heterostructures
367
(a)
(b)
(c)
(d)
(e)
Fig. 12.24 Heterostructures with different layer sequences (band gap engineering). a quantum well (QW), b multiple
quantum well (MQW), c superlattice (SL), d single-barrier tunneling structure, e double-barrier tunneling structure
Fig. 12.25 Ultrathin
heterostructures: a
Cross-sectional TEM of a
MOVPE-grown
short-period superlattice
(SPS) of InAs layers in
GaAs 1−x N x ). In high
resolution (right image),
the individual rows of
atoms can be seen. From
[1177]. b, c Cross-section
STM image of 2 ML InAs
on GaAs; the segregation
of In into the top layer is
visible atom by atom.
Adapted from [1178]
(a)
InAs
367
(a)
(b)
(c)
(d)
(e)
Fig. 12.24 Heterostructures with different layer sequences (band gap engineering). a quantum well (QW), b multiple
quantum well (MQW), c superlattice (SL), d single-barrier tunneling structure, e double-barrier tunneling structure
Fig. 12.25 Ultrathin
heterostructures: a
Cross-sectional TEM of a
MOVPE-grown
short-period superlattice
(SPS) of InAs layers in
GaAs 1−x N x ). In high
resolution (right image),
the individual rows of
atoms can be seen. From
[1177]. b, c Cross-section
STM image of 2 ML InAs
on GaAs; the segregation
of In into the top layer is
visible atom by atom.
Adapted from [1178]
(a)
InAs