Microdefects (MD) formed in GaP single crystals during post-crystallization cooling were studied by X-ray diffuse scattering method and transmission electron microscopy (TEM). Analysis of the shape of isodiffuse contours suggests a mechanism of the MD formation. According to the mechanism, the MD are formed by the association of (GaP)_i molecules which are the interstitial type MDs and gallium and phosphorus vacancies (V_Ga and V_P). The dislocation loops observed by TEM, in principle, confirm the suggested mechanism of MD formation. Similarity of the behaviour of X-ray diffuse scattering for gallium arsenide grown with excess of gallium and gallium phosphide which usually grows with a great excess of gallium suggests a similarity between the MD formation mechanisms for settling?out of a superfluous cation for the whole group of А^NB^8-N compounds. Sulphur doping in a concentration of up to 2 · 10¹⁹ cm^-3 does not change the mechanism of the interstitial type MD formation, but very likely decreases the probability of vacancy-type MD formation.

1. Bublik, V. T. Nestehiometrija, sobstvennye tochechnye defekty i mikrodefekty v soedinenijah A^IIIB^V / V. T. Bublik, M. G. Mil'vidskij // Materialovedenie. - 1997. - N 2. - P. 21- 29.
2. Filatov, P. A. Izuchenie mehanizma obrazovanija mikrodefektov v monokristallah GaAs, vyrawennyh iz rastvora- rasplava s izbytkom gallija / P. A. Filatov, V. T. Bublik, A. V. Markov, K. D. Werbachev, M. I. Voronova // Izv. vuzov. Materialy jelektron. tehniki. - 2008. - N 4. - P. 57—61.
3. Filatov, P. A. Issledovanie mikrodefektov v monokristallah GaP i GaP(Zn), vyrawennyh metodom ChZhGR / P. A. Filatov, V. T. Bublik, T. I. Markova, K. D. Werbachev, M. I. Voronova / Kristallografija. - 2008. - Vol. 53, N 2. - P. 284—292.
4. Filatov, P. A. O politropii sery v fosfide gallija / P. A. Filatov, V. T. Bublik, Ju. E. Belousova, K. D. Werbachev, M. I. Voronova // Izv. vuzov. Materialy jelektron. Tehniki. - 2008. - N 3. - P. 34—37.
5. Bublik, V. T. Issledovanie osobennostej obrazovanija mikrodefektov v termicheski obrabotannyh bezdislokacionnyh plastinah kremnija bol'shogo diametra metodom diffuznogo rassejanija rentgenovskih luchej / V. T. Bublik, S. Ju. Macnev, K. D. Werbachev, M. V. Mezhennyj, M. G. Mil'vidskij, V. Ja. Reznik // Fizika tverdogo tela. — 2003. - Vol. 45, Issue 10. - P. 1825—1832.
6. Krivoglaz, M. A. Difrakcija rentgenovskih luchej i nejtronov v neideal'nyh kristallah / M.A. Krivoglaz. - Kiev : Nauk. dumka, 1983.
7. Gorjunova, N. A. Slozhnye almazopodobnye poluprovodniki / N. A. Gorjunova. - M. : Sovetskoe radio, 1968.
8. Belousova, Ju. E. / Ju. E. Belousova, T. I. Ol'hovikova, F. R. Hashimov, Ju. A. Okunev // Jelektron. tehnika. Ser. Materialy. - 1987. - Vol. 226, N 8. - P. 16—20.
9. Quadbeck, P. Effect of dopant atoms on the roughness of III—V semiconductor cleavage surfaces/ P. Quadbeck, P. Ebert, K. Urban, J. Gebauer, R. Krause-Rehberg// J. Appl. Lett. - 2000. - V. 76, N 3. - P. 300—303.
10. Kristallohimicheskie, fiziko-himicheskie i fizicheskie svojstva poluprovodnikovyh vewstv. - M. : Izd-vo standartov, 1973.