I n low-ohmic n-type ZnSe crystals with the room temperature specific resistance of (3 t o 5) rZ cm and electron concentration from 3 x 10l6 to 2 x 10l6Hall-effect, electrical conductivity, and charge carrier mobility is investigated in the temperature interval from 10 t o 300 K. The basic parameters of the samples are determined. It is found from the experimental data that the mobility is higher than the theoretical value in the investigated temperature range. It is argued that in the region of ionized impurity scattering this descrepancy between theory and experiment is due t o the inadequacy of known scattering based on the Born approximation, as for ZnSe this approximation is valid at T > 140 K, where the phonon scattering is predominant. To square the theory with the experiment in the phonon scattering region a polaron effect is taken into account, which manifests itself in renormalization of the carrier effective mass as well as in alteration of the mobility temperature dependence due t o the effect of screening of the interaction with polar vibrations. The theoretical consideration of this question is given which allows t o bring the theory and the experiment to a satisfactory correspondence.
OPTICAL PROPERTIES OF DOUBLE-LAYER STRUCTURE PHTHALOCYANINE-TETRACYANOQUINODIMETHANE
Z. I. Kazantseva, E. G. Bortchagovsky, I. A. KoshetsOptical properties of double-layer structures consisting of Cu-phthalocyanine vacuum evaporated film and Langmuir-Blodgett film of 7,8, were investigated by ellipsometry, photoconductivity and optical transmission. The obtained results indicate strong interaction between the materials; the resulting optical properties cannot be presented as the sum of those of the particular components. Two new effective absorption bands at 1.08 and 2.85 eV were found for such structures. The band at 2.85 eV coincides with a measured peak in photocurrent spectrum, which supports the idea on a charge transfer complex formation between Cu-phthalocyanine to TCNQ. Ìåòîäàìè åë³ïñîìåòð³¿, ôîòîïðîâ³äíîñò³ òà îïòè÷íîãî ïîãëèíàííÿ äîñë³äaeåí³ îïòè÷í³ âëàñòèâîñò³ á³øàðîâèõ ñòðóêòóð, óòâîðåíèõ òîíêèìè ïë³âêàìè íàïîðîøåíîãî â âàêóóì³ ôòà-ëîö³àí³íó ì³ä³ (CuPc) òà ïë³âêàìè Ëåíãìþðà-Áëîäaeåòò ïåíòàäåöèë 7,7,8,8-òåòðàö³àíî-1,4-õ³íîäèìåòàíàó (ïåíòàäåöèë TCNQ). Îòðèìàí³ ðåçóëüòàòè âêàçóþòü íà íàÿâí³ñòü âçàºìî䳿 ì³ae ðå÷îâèíàìè; îïòè÷í³ âëàñòèâîñò³ ñèñòåìè íå ìîaeóòü áóòè ïðåäñòàâëåí³ ÿê ïðîñòà ñóïåð-ïîçèö³ÿ ñêëàäîâèõ êîìïîíåíò. Ó ñïåêòð³ ïîãëèíàííÿ ñòðóêòóðè âèÿâëåíî äâ³ íîâ³ ñìóãè 1.08 ³ 2.85 eV. Ñìóãà 2.85 eV ñï³âïàäຠç ï³äâèùåííÿì ñèãíàëó â ñïåêòð³ ôîòîïðîâ³äíîñò³, ùî ñâ³-ä÷èòü íà êîðèñòü ã³ïîòåçè ïðî óòâîðåííÿ êîìïëåêñó ç ïåðåíîñîì çàðÿäó ì³ae CuPc ³ TCNQ.Êëþ÷îâ³ ñëîâà: îðãàí³÷í³ íàï³âïðîâ³äíèêè, åë³ïñîìåòð³ÿ, îïòè÷íà ñïåêòðîñêîï³ÿ, ôîòî-ïðîâ³äí³ñòü.Z. I. Kazantseva, E. G. Bortchagovsky, I. A. Koshets
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