L. R Wallenberg, F. Lenrick, M. Ek, D. Jacobsson, L. Samuelson* and K. Dick Thelander
nCHREM, Inst. for Chemistry and *Solid State Physics, Lund University, Sweden
Semiconductor nanowires (NWs) and nanopyramids have a clear potential for areas like optronics, wrap-gate FETs, solar cells and efficient white LEDs. However some hurdles must be passed on the way. Lattice misfit, which causes severe dislocations, is one of the major obstacles when growing thin layers on substrates. For LED:s based on III-nitrides, intended to fill “the green gap”, we will show that this obstacle can be overcome by growth through nanoscale apertures, forming nanopyramids with high perfection. Another way to overcome the lattice misfit is to grow 1-D nanowires. Nanowires can accept much larger misfits and metal nanoparticle catalyzed growth by MOCVD has been a very successful approach to build nanoelectronics and devices with the high accuracy needed for full scale production. Recently, a new method for growth, Aerotaxy[1] has been invented, which eliminates the need of expensive substrates and allows much higher growth rates than epitaxial growth. Theoretical modeling for Aerotaxy growth is still largely undeveloped, which is why observation of growth on the atomic scale, while varying parameters like temperature, pressure and ratio of the III and V element precursor gases is most helpful[2]. We will show preliminary results from an in-house constructed closed cell[3] as well as a dedicated Environmental TEM, based on a 300 kV FEG with an aplanatic image aberration corrector. A gas supply system will deliver 9 different gases at the specimen area with a pressure of at least 1 Pa, and the specimen area can be heated to >700ºC.
[1] Heurlin M, Magnusson M. H, Lindgren D., Ek M., Wallenberg L R, Deppert K, Samuelson L. Continuous gas-phase synthesis of nanowires with tunable properties. Nature 492, 90, 2012
[2] Jacobsson D., Panciera F., Tersoff, J., Reuter, M.C., Lehmann S., Hofmann, S., Dick, K.A. and Ross, F. M. Interface dynamics and crystal phase switching in GaAs nanowires. Nature 531, 317–322, 2016
[3] Lenrick, F.; Ek, M.; Deppert, K., Samuelson L.,Wallenberg L R. Straight and kinked InAs nanowire growth observed in situ by transmission electron microscopy. NANO Research, 7(8), 1188-1194, 2014
