Hot electron interactions in nanostructures
Author(s)
Advisor
Ellialtioğlu, RecaiDate
1997Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
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Abstract
Modern semiconductor growth and processing techiques have provided the
capability of fabricating a huge variety of devices which have atomically precise
layered structures and lateral patterns with nanometer sizes. This not only
provided novel device possibilités but also opened a new field in condensed matter
physics, so called mesoscopics. It does not seem likely that the mesoscopic
electronic devices will be available in the near future. Two main obstacles for
mesoscopic electronics are the low temperature requirements and the breakdown
of the phase coherence of the carriers as their energies exceed the Fermi level.
This strongly suggests the investigation of the excited carriers with energies well
in excess of their thermal equilibrium energy as the dimensions shrink. In this
thesis, the interactions of hot electrons in semiconductor and metal structures
with deep submicron characteristic dimensions have been studied. Tunneling
Hot Electron Transfer Amplifier (THETA) constructed by abrupt semiconductur
heterojunctions is a perfect system to analyze the interaction of hot electrons
with cold electrons and the other possible excitations in solids. Recently, it
has been discovered that an electron multiplication effect took place in such
devices under certain conditions and resulted in a transfer ratio of greater than unity. In this work a novel fabrication technique has been developed. It would
make it possible to utilize this effect for fabrication of a high frequency oscillator
in the THz regime, in a future work. In addition, a kind of lateral THETA
device has been constructed using a Two Dimensional Electron Gas structure.
Electron multiplication effect for the first time has been observed in 2DEG
structures. Moreover, the dependence of the effect on parameters such as injection
energy, emitter and collector barrier heights and electron transit length has been
investigated. The other direction of the work has been the investigation of
metal wires under extremely high current densities. A strong nonlinearity in
conductivity is introduced when a free standing submicrometer wire is biased to
heat upto very high temperatures. The geometry of two crossing wires has been
investigated under this condition.