%0 Thesis
%A Kamil, Sladek
%T Realization of III-V semiconductor nano structures towards more efficient (opto-) electronic devices
%I RWTH Aachen
%V Dr.
%C Jülich
%M FZJ-2014-00577
%P 100
%D 2013
%Z RWTH Aachen, Diss., 2013
%X Solid state electronics and their application in personal computers, smartphones, digital
%X cameras and entertainment devices (to name a few) have gained such a rapid progress that
%X it’s already barely imaginable how our future technological environment will evolve in the next
%X few years. In parallel, however, concerns about excessive use of the world’s limited natural
%X energy resources has led to a rethinking with respect to the design and production of future
%X electronics.
%X One of the most promising solutions to further improve the efficiency of electronics is the
%X combination of the well established silicon technology with III-V semiconductor nano structures
%X which have been extensively investigated in various fields for the last few decades. InAs nano
%X structures, in particular, are intrinsically conductive due to their characteristic conduction band
%X profile, caused by surface states. The materials high bulk carrier mobility gives rise to expect a
%X significant boost in efficiency of electronic devices that employ InAs nano structures.
%X In this work, three different aspects of device improvement are addressed: the exchange of
%X channel material in traditional CMOS, the development of new nanostructure based concepts
%X and the use of direct band gap properties for more cost-effective sensing devices. The
%X established SA MOVPE of III-V nano structures on III-V substrates serves as a starting point.
%X Systematic experiments are conducted in order to address several significant questions
%X regarding the suitability of III-V nano structures as building blocks for future electronic devices.
%X It is found that a large variety of free-standing InAs nanowires with different properties can be
%X produced in an ordered and controlled fashion. The results show that uniform InAs nanowires
%X with a high aspect ratio can be produced selectively on GaAs(111)B and GaAs(110) oriented
%X surfaces, the latter being also a natural cleaved edge direction of industrially used Si(001)
%X substrates. In addition, very thin InAs nanowires with diameters down to 20 nm are obtained
%X as a side effect on non-structured cleaved-edge sidewalls of GaAs(001). N-type doping with
%X disilane is found to have a general impact on the nanowire morphology, resulting in a reduced
%X height vs. diameter aspect ratio with an increased amount of doping applied during deposition.
%X It is observed that all wires exhibit an intrinsic conductivity with an ohmic behavior which is
%X further increased after doping. Also, the nanowire diameter is found to be a potential
%X parameter to tune their electronic properties. A series of experiments with different growth
%X parameters and the successive characterization of the nanowires‘ crystal structure reveal that
%X different group-V partial pressures affect the formation of stacking faults and the crystal‘s
%X wurtzite to zinc blende ratio. A significant step to combine the gained knowledge on controlled
%X bottom-up InAs nanowire fabrication and benefits of SA MOVPE in N2 ambient with current
%X silicon technology is the transition of InAs growth to silicon substrates. The technique of flow
%X modulated epitaxy is adopted from MOVPE growth in hydrogen ambient and adapted and
%X optimized for growth in N2 in order overcome the lack of polarity on silicon. As a result, InAs
%X nanowire growth on Si(111) is carried out with a high yield of vertical wires.
%X After the investigation of free standing InAs nanowires mainly for concepts exceeding
%X CMOS, a methodology for the deposition of lateral InAs nano structures on silicon by SA
%X MOVPE was presented, aimed towards the exchange of channel material in current planar
%X electronic devices. Growth parameters adopted from GaAs/InAs core-shell nanowire growth
%X are applied to a variety of differently oriented and patterned substrates. The obtained lateral
%X structures are characterized with respect to morphology, crystal structure and electronic
%X properties. High crystallinity and conductivity are found and discussed in comparison to the
%X results obtained from vertical nanowires.
%X Finally, quantum cascade structures based on ternary III-V semiconductors with high indium
%X content are investigated with respect to single mode emission for gas sensing applications. It
%X is found that curved laser waveguides are capable of single mode emission which is explained
%X by the interaction of coupled cavities, resulting in strong side mode suppression. The
%X monolithic approach without need for complicated sample processing has tremendous
%X potential for the fabrication of cost effective and portable gas sensing devices.
%K Dissertation (GND)
%F PUB:(DE-HGF)11
%9 Dissertation / PhD Thesis
%U https://juser.fz-juelich.de/record/150523