Nanoobjects microscopy 

Selective MW detecting using the surface electrons over liquid helium on structured substrate  
V. A. Nikolaenko, Ya. Yu. Bezsmolny
B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, Prospekt Nauky, 47, Kharkov 61103, Ukraine
E-mail: nikolaenko@ilt.kharkov.ua	
Some fundamental and applied problems of nanoelectronic can be solving by surface electrons (SE) over layer helium on substrate. SEs is formed at a small potential well on border of matters and has in normal directional the hydrogenous energy spectrum of scale ~ 10 K :  ħωl=mΛ2/2 ħ2l2  were Λ=[e2 ( εHe -1)]/[4(εHe +1)]  (ħ is Plank’s constant; e and m are charge and mass of electron;  εHe is helium permittivity and l=1;2;3…). The modulation of substrate properties lowers the dimensionality of SE system up to quantum dot (QD).   
  Here proposed for the detecting of a microwave (MW) radiation the utilization of harmonic spectrum QD - SEs over the distorted helium surface in pores of structured substrate (figure). The transport of SE over silicon structured substrate was considered early [1]. The analytical model of a cylindrical pore along field, E shows the preferential localization of electrons near the pores. 
 The selective MW frequency coincide with along harmonic spectrum of SE expressed as  ω=(eE/mR)1/2 . Here the value  R=2α/ρgH  is the distortion radius of helium surface over pores (α and ρ are surface tension and density of helium, correspondently; g is acceleration of gravity force and H is distance between surfaces of substrate and helium under it). The spectrum of scale (0.1  - 1K) is governed by values R, E  and by charge on substrate too. The stimulated by MW- radiation the transition between a SE states changes the local potential is fixed by sensitive chip. 
It has possible the selective detecting of sub-mm radiation too by SE hydrogenlike energy spectrum of SE. The Umov-Poiting vector must be tilted to surface here.  
 The composition of device is: the porous silicon substrate; reading electrodes (pixels) is connected to potential sensitive sensors (field effect transistors, one electron transistor - SET, .....) on the rear side; the potential grid above the substrate and a source of free electrons. 

1.	A.V. Smorodin, V.A. Nikolaenko, S.S. Sokolov, L.A. Karachevtseva, and O.O. Lytvynenko.  Transport properties of surface electrons over structurized substrate // Low Temp. Phys.- 2012.- 38,  P. 1158-1166.