Sensitivity of carrier spectrum in semiconducting nanowire to adsorbed molecules

Victor A. LYKAH 1Evgen S. SYRKIN 2

1. National Technical University"Kharkov Polytechnical Institute", 21 Frunze str., Kharkov 61002, Ukraine
2. Institute for Low Temperature Physics, 47 Lenin ave., Kharkov 61103, Ukraine


Optical and conducting properties of nanoobjects are conditioned with a set of energy quantum levels and filling of these levels with carriers. Tunneling through an individual nanowire is extremely sensitive to the charge state and to the appearance of adsorbed layers.
The present work considers quantum levels of an uncompensated charge carrier inside a perfect semiconductor quantum wire covered by gas of an adsorbed molecules with intrinsic electric dipole moments. The quantum wire may be a usual intrinsic semiconductor or a carbon nanotube with large mean free path. The molecules are redistributed under inhomogeneous carrier’s electric field, as a result the stationary Schrodinger equation becomes nonlocal and nonlinear. In the limit of relatively small deviation of the molecules concentration the longitudinal quantization is reduced to the spectral problem for nonlinear Schrodinger equation in the rectangular well. Variables are divided and solution is written in terms of elliptic functions. The selfconsistent system of equations could be reduced to closed set of two transcendent equations for elliptic modulus and the wave number (that gives the energetic spectrum of the carrier) as functions of complete elliptic integrals of the first and second kind.
The main features of solution: 1) the higher the interaction is, the more the nonlinearity is, 2) the strongest effect of the nonlinear interaction does occur for lowest levels while the effect for top levels disappears, 3) the effect should be more pronounced for heavier holes. 4) If the adiabatic approximation is satisfied the carrier’s spectrum changes with retard which depends on diffusion time.
For the strong interaction all states of the carrier are localized and could be responsible for the decrease of conductivity in chemisorption wire sensors.


Presentation: poster at E-MRS Fall Meeting 2004, Symposium G, by Victor A. LYKAH
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-05-17 08:27
Revised:   2009-06-08 12:55