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Disertacija skirta nepusiausvirųjų krūvininkų dinamikos tyrimams SiC, GaN bei deimantuose naudojant šviesa indukuotų dinaminių gardelių, diferencinio pralaidumo, diferencinio atspindžio bei fotoliuminescencijos metodikas. Taipogi pristatomos naujos sugerties koeficiento matavimo bei gyvavimo trukmės mikroskopijos metodikos. Tyrimai atlikti plačiame nepusiausvirųjų krūvininkų tankių ir temperatūrų intervale esant vienfotoniam bei dvifotoniam sužadinimui. Nustatytas stiprus krūvininkų difuzijos koeficiento priklausomumas nuo krūvininkų tankio ir temperatūros. Jis paaiškintas fononine sklaida, krūvininkų tarpusavio sąveikos procesais bei išsigimimu. Buvo nustatyta, kad netiesiatarpiuose SiC ir deimanto puslaidininkiuose prie mažų sužadinimų rekombinacija yra ribota taškiniais bei paviršiniais defektais, o GaN dominuoja rekombinacija ant tarpkristalitinių ribų. Taipogi pasireiškė netiesinis Ože rekombinacijos procesas, kuris prie žemų sužadinimų buvo sustiprintas kulonine sąveika bei susilpnintas prie didelių dėl elektron-fononinės sąveikos ekranavimo bei išsigimimo. Fotoliuminescencijos efektyvumas parodė, kad spindulinės rekombinacijos koeficientas GaN mažėja nuo sužadinimo, tuo tarpu SiC jis nuo žadinimo nepriklauso. Kompensuojančių defektų (aliuminio SiC ir boro deimante) koncentracijos ir aktyvacijos energijos nustatytos stebint jų sąlygotos sugerties įsisotinimą bei jų signalo relaksacijos spartos priklausomybę nuo temperatūros. The thesis is dedicated to investigation of carrier dynamics in SiC, GaN and diamond by using light-induced transient gratings, differential transmittivity, differential reflectivity and photoluminescence techniques. Also new absorption coefficient measurement and carrier lifetime microscopy techniques are presented. The experimental studies were performed in a wide range of excess carrier densities and temperatures under single- and two- photon excitation conditions. Strong diffusion coefficient temperature and injection dependences were determined. They were explained by phonon scattering, inter-carrier interaction processes and degeneracy. It was determined, that in indirect-gap SiC and diamond semiconductors at low injections lifetime is limited by point and surface defects, while in GaN recombination on grain boundaries prevails. Also nonlinear Auger recombination coefficient was observed. It was Coulombically enhanced at low injections and screened at high ones. Photoluminescence efficiency revealed radiative recombination coefficient reduction with injection in GaN. On the other hand, in SiC radiative coefficient was injection independent. Compensating defect (aluminum in SiC and boron in diamond) concentrations and activation energies were determined from their absorption saturation and recovery rate temperature dependences.

The thesis is dedicated to investigation of carrier dynamics in SiC, GaN and diamond by using light-induced transient gratings, differential transmittivity, differential reflectivity and photoluminescence techniques. Also new absorption coefficient measurement and carrier lifetime microscopy techniques are presented. The experimental studies were performed in a wide range of excess carrier densities and temperatures under single- and two- photon excitation conditions. Strong diffusion coefficient temperature and injection dependences were determined. They were explained by phonon scattering, inter-carrier interaction processes and degeneracy. It was determined, that in indirect-gap SiC and diamond semiconductors at low injections lifetime is limited by point and surface defects, while in GaN recombination on grain boundaries prevails. Also nonlinear Auger recombination coefficient was observed. It was Coulombically enhanced at low injections and screened at high ones. Photoluminescence efficiency revealed radiative recombination coefficient reduction with injection in GaN. On the other hand, in SiC radiative coefficient was injection independent. Compensating defect (aluminum in SiC and boron in diamond) concentrations and activation energies were determined from their absorption saturation and recovery rate temperature dependences.