Photoluminescence and vibrational properties of nanostructured ZnSe templates

Abstract

Electrochemical etching of pores in as-grown and doped n-type ZnSe substrates is reported. To dope the samples the as-grown semi-insulating substrates were annealed in a Zn melt containing Al impurity at concentrations ranging from 0.1 to 40 at.%. We demonstrate the growth of arrays of parallel pores with diameters ranging from several hundreds of nanometers down to 40 nm. According to the dependence of the anodic current on the applied potential, the pore growth is found to be mediated by oxide formation. LO-phonon-plasmon coupling and the emergence of the Fröhlich-type surface phonon mode are studied by Raman spectroscopy of annealed and electrochemically treated samples. The position of the Fröhlich mode is found to be identical in porous samples with different diameters of pores and skeleton wall thicknesses, in accordance with the effective medium theory when applied to porous materials with identical semiconductor skeleton relative volume concentration. The photoluminescence analysis of the prepared porous structures is indicative of effective passivation of the porous skeleton surface during anodization while Raman scattering evidences a decrease in the free carrier concentration and neutralization of impurity centers in the porous skeleton walls.

(Invited) Modeling Some "Meta" Aspects of Pore Growth in Semiconductors

“…Currentline pores have so far been found in InP and GaP (2, 12 -16), again for a large variety of electrolytes. The classification can be easily extended to pores obtained in II-VI semiconductors (17,18), which closely resemble the currentline pores found in InP, as well as to Si and Ge, where most pore types have always been of the crysto pore type (19 -21), but currentline pore growth can also be obtained (22).…”

Macroporous Semiconductors

“…To give just a few examples for the latter point: pore types completely different from anything else encountered so far were discovered in GaP in [29], in Ge in 2009 [30], and in ZnSe in [31,32]. The fact that these pore types were neither predicted nor understood at present, nicely illustrates the first point.…”

“…Reading through the several thousand pages quoted above will not only provide a lot of information about porous semiconductors (even more can be found in the by now several thousand regular papers), but will also illustrate two pertinent points: i) there are still many open questions concerning, e.g., formation mechanisms and properties of porous semiconductors, and ii) there has been much progress in theory, techniques, and experimental discoveries in recent years. To give just a few examples for the latter point: pore types completely different from anything else encountered so far were discovered in GaP in [ 29 ], in Ge in 2009 [ 30 ], and in ZnSe in [ 31 , 32 ]. The fact that these pore types were neither predicted nor understood at present, nicely illustrates the first point.…”

Luminescent materials based on semiconductor compound templates for random laser applications

“…13b. The possibility to change the characteristic size of the ZnSe porous template in the range from 40 nm to 1 µm has been recently demonstrated [31]. The high optical quality of the produced ZnO material on the basis of ZnSe templates is demonstrated by the PL analysis (Fig.…”