  InAs/GaSb heterostructure is one of the systems where quantum spin Hall
effect is predicted to arise. However, as confirmed by recent experimental
studies, the most significant highlight of the effect i.e., the conductance
quantization due to non-trivial edge states is obscured by spurious
conductivity arising from trivial edge states. In this work, we present
experimental observation of strong localization of trivial edge modes in an
InAs/GaSb heterostructure which was weakly disordered by silicon delta-like
dopants within the InAs layer. The edge conduction which is characterized by a
temperature-independent behavior at low temperatures and a power law at high
temperatures is observed to be exponentially scaled with the length of the
edge. Comprehensive analysis on measurements with a range of devices is in
agreement with the localization theories in quasi one-dimensional electronic
systems.
