[PDF]    http://dx.doi.org/10.3952/lithjphys.48301

Open access article / Atviros prieigos straipsnis

Lith. J. Phys. 48, 249–258 (2008)

E. Montrimas, R. Rinkūnas, S. Kuskevičius, and R. Purlys
Faculty of Physics, Vilnius University, Saulėtekio 9, LT-10222 Vilnius, Lithuania
E-mail: ringaudas.rinkunas@ff.vu.lt

Received 6 June 2007; revised 4 July 2008; accepted 18 September 2008

After exposure of amorphous selenium islands to luminous flux of 1\cdot106 lx, they do not become crystalline, but remain amorphous. However, light stimulates polymerization of molecules in those islands. For this reason, heating of a layer that is exposed to light does not cause a decrease of the mean thickness of the layer, but heating of the layer in the dark causes a decrease of its mean thickness. Therefore, the mean thickness of the illuminated layer is 3 to 4 times greater than the mean thickness of the layer in the dark. In addition, the fraction of the substrate covered by the islands is 1.5 to 2 times larger in the exposed layer than in the unexposed layer. However, illumination of a continuous layer speeds up its transformation into an island-type layer. Therefore, in order to obtain an extremely thin continuous layer of amorphous selenium, during growth of the layer it must be exposed to light only until it becomes continuous. Starting from that moment, the light must be switched off.
Keywords: thin film, selenium, island, polymer
PACS: 68.37.-d, 68.43.Jk, 68.55.Ac

E. Montrimas, R. Rinkūnas, S. Kuskevičius, R. Purlys
Vilniaus universiteto Fizikos fakultetas, Vilnius, Lietuva

Apšvietus amorfines seleno saleles 1\cdot106 lx šviesos srautu, jos netampa kristalinėmis, o išlieka amorfinės, tačiau šviesa skatina jose molekulių polimerizaciją. Dėl šios priežasties, kaitinant pavyzdėlį, apšviesto sluoksnio vidutinis storis nemažėja, o esančio tamsoje – mažėja. Apšviestas sluoksnis tampa vidutiniškai 3–4 kartus storesnis už esantį tamsoje. Taip pat ir užpildyta salelėmis padėklo dalis yra 1,5–2 kartus didesnė apšviestame sluoksnyje, negu esančiame tamsoje. Tačiau apšvietus ištisinį sluoksnį, šis greičiau persitvarkys į salelinį. Taigi, norint pagaminti kuo plonesnį ištisinį amorfinio seleno sluoksnį, reikia apšviesti augimo metu tik tol, kol jis taps ištisiniu, o tada šviesą išjungti.

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