Unintentional High-Density p-Type Modulation Doping of a GaAs/AlAs Core–Multishell Nanowire

The distribution of dopants significantly influences the properties of semiconductors, yet effective modulation and separation of p-type and n-type dopants in homogeneous materials remain challenging, especially for nanostructures. Employing a bond orbital model with supportive atomistic simulations, we show that axial twisting can substantially modulate the radial distribution of dopants in Si nanowires (NWs) such that dopants of smaller sizes than the host atom prefer atomic sites near the NW core, while dopants of larger sizes are prone to staying adjacent to the NW surface. We attribute such distinct behaviors to the twist-induced inhomogeneous shear strain in NW. With this, our investigation on codoping pairs further reveals that with proper choices of codoping pairs, e.g. B and Sb, n-type and p-type dopants can be well separated along the NW radial dimension. Our findings suggest that twisting may lead to realizations of p–n junction configuration and modulation doping in single-crystalline NWs.

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Simple theoretical model for the temperature stability of InAs/GaAs self-assembled quantum dot lasers with different p-type modulation doping levels

Applied Physics Letters ◽

10.1063/1.3003874 ◽

2008 ◽

Vol 93 (16) ◽

pp. 161103 ◽

Cited By ~ 9

Author(s):

C. Y. Jin ◽

H. Y. Liu ◽

Q. Jiang ◽

M. Hopkinson ◽

O. Wada

Keyword(s):

Theoretical Model ◽

Quantum Dot ◽

Temperature Stability ◽

Quantum Dot Lasers ◽

Modulation Doping ◽

Simple Theoretical Model ◽

Self Assembled ◽

P Type

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Preferential crystal growth of germanium by solid phase crystallization

Canadian Journal of Physics ◽

10.1139/cjp-2013-0588 ◽

2014 ◽

Vol 92 (7/8) ◽

pp. 576-581 ◽

Cited By ~ 5

Author(s):

Mikuri Kanai ◽

Yuji Kojima ◽

Masao Isomura

Keyword(s):

Crystalline Silicon ◽

Solid Phase ◽

Electron Beam Evaporation ◽

High Density ◽

Solid Phase Crystallization ◽

Air Exposure ◽

Preferential Growth ◽

Practical Applications ◽

Si Substrates ◽

P Type

We have investigated the preparation of crystalline germanium films by the solid phase crystallization (SPC) of amorphous germanium (a-Ge) precursor on single crystalline silicon substrates. The a-Ge precursor easily incorporates the impurities from the surface exposed to the air, and the impurities affect the crystallinity after the SPC. In the a-Ge precursor prepared by Knudsen-cell evaporation, the preferential crystalline growth following the Si substrates is disturbed by the high density of impurities and the random crystalline structures are formed. The a-Ge precursors prepared by electron beam evaporation have high impurity concentrations only near the surface because the impurity diffusion is slow because of the relatively high density. The preferential growth is successfully obtained in a-Ge precursor prepared on n-type Si substrates, although the random crystallization is slightly observed on p-type Si substrates. By sufficiently reducing the impurity concentrations by avoiding the air exposure, the preferential growth can be promoted on p-type Si substrates. The impurity incorporation because of the air exposure is sufficiently reduced for the preferential growth by covering a-Ge with a-Si blocking layers. This method is effective for future practical applications of SPC Ge films.

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