Temperature dependence of the absorption edge of synthetic diamond

Using optical spectroscopy in the spectral range from 200 to 300 nm, the absorption edge and transmission spectra of 7 samples of synthetic diamond of IIa type in the temperature range from 12 K to 470 K was studied. Using numerical methods, the temperature dependences of optical absorption into the free exciton state were obtained for negative and positive phonon branches

Photoluminescence and optical absorption of diamond samples containing NV centers

NV center is an impurity defective complex in diamond, obtained by irradiating with highenergy electrons samples containing nitrogen in a substituting position and post radiating annealing. NV centers are observed in several charge states negative (zero phonon line at 638 nm), neutral (ZPL at 575 nm), and, possibly, positive (ZPL at 533 nm). NV centers in diamond are candidates for qubits for quantum computing, the basis of high speed magnetometric sensors, sources of single photons, and also emitting centers of optically active laser media

Impact of the graded-gap layer on the admittance of MIS structures based on MBE-grown n-Hg1-xCdxTe (x = 0.22-0.23) with the Al2O3 insulator

The impact of the presence of the near-surface graded-gap layers with an increased content of CdTe on the admittance of MIS structures based on MBE-grown n-Hg1–xCdxTe (x = 0.22–0.23) with the Al2O3 insulating coating has been experimentally studied. It has been shown that the structures with a gradedgap layer are characterized by a deeper and wider capacitance dip in the low-frequency capacitance–voltage (CV) characteristic and by higher values of the differential resistance of the space-charge region than the structures without such a layer. It has been found that the main features of the hysteresis of capacitance dependences typical of the graded-gap structures with SiO2/Si3N4 are also characteristic of the MIS structures with the Al2O3 insulator. The factors that cause an increase in the CV characteristic hysteresis upon formation of the graded-gap layer in structures with SiO2/Si3N4 or Al2O3 are still debatable, although it may be assumed that oxygen plays a certain role in formation of this hysteresis

ЭЛЕКТРОФИЗИЧЕСКИЕ И ФОТОЭЛЕКТРИЧЕСКИЕ ХАРАКТЕРИСТИКИ МДП–СТРУКТУР НА ОСНОВЕ ГЕТЕРОЭПИТАКСИАЛЬНОГО HgCdTe, ПОЛУЧЕННОГО МЕТОДОМ МОЛЕКУЛЯРНО–ЛУЧЕВОЙ ЭПИТАКСИИ, C НЕОДНОРОДНЫМ РАСПРЕДЕЛЕНИЕМ СОСТАВА

The electro-physical and photoelectrical properties of MIS structures based on HgCdTe MBE with non-uniform distribution of composition were experimentally investigated. It is shown that near-surface graded-gap layers with elevated composition strongly affect on dependencies of the capacitance and the photo-emf versus the bias voltage and frequency for the MIS structures based on n-Hg1-xCdxTe (x = 0.21—0.23). The characteristics of MIS structures based on n-Hg0.7Cd0.3Te with periodically located regions with high composition were investigated and it is shown that these regions are most strongly affect the characteristics of MIS structures when their location near the boundary of the insulator−semiconductor. The electrical properties of MIS structures based on n-Hg1-xCdxTe (x = 0.62—0.73) with region with lower composition were experimentally studied.Экспериментально исследованы электрофизические и фотоэлектрические свойства МДП-структур на основе HgCdTe, полученного методом молекулярно-лучевой эпитаксии, с неоднородным распределением состава. Показано, что для МДП-структур на основе n-Hg1-xCdxTe (x = 0,21-0,23) приповерхностные варизонные слои с увеличенным содержанием СdTe на поверхности сильно влияют на зависимости емкости и фотоЭДС от напряжения смещения и частоты. Исследованы характеристики МДП-структур на основе n-Hg0,7Cd0,3Te с периодически расположенными областями резко повышенного содержания CdTe барьерного типа и показано, что эти области оказывают влияние на характеристики МДП-структур при их расположении вблизи границы раздела диэлектрик—полупроводник. Экспериментально изучены электрические свойства МДП-структур на основе n-Hg1-xCdxTe (x = 0,62-0,73) с областями пониженного содержания CdTe в приповерхностной области типа потенциальных ям

Admittance of MIS structures based on graded-gap MBE HgCdTe with Al2O3 insulator

The paper presents the results of studies of the admittance of MIS structures based on heteroepitaxial MBE n (p)-Hg0.78Cd0.22Te with insulator coating SiO2/Si3N4 and Al2O3 in the test signal frequency range 10 kHz-1 MHz at temperatures ranging from 8 to 220 K. The main parameters of MIS structures with different insulators were determined. MIS structures with Al2O3 have a large enough insulator capacitance (compared to SiO2/Si3N4), a significant modulation capacitance on the CV characteristics, high dielectric strength and low values of the flat-band voltage. The effective charge density found from the value of the flat-band voltage and slow interface trap density for structures with Al2O3 comparable with the corresponding densities for structures with SiO2/Si3N4

Influence of As+ Ion implantation on properties of MBE HgCdTe near-surface layer characterized by metal–insulator–semiconductor techniques

The effect of As+ ion implantation on the electrical properties of the near-surface layer of n-HgCdTe films grown by molecular beam epitaxy (MBE) on Si (310) substrates was experimentally studied. A specific feature of MBE n-Hg0.78Cd0.22Te films is the presence of near-surface graded-gap layers with a high CdTe content, formed during epitaxial growth. The properties of as-grown films and films after As+ ion implantation with ion energy of 200 keV and fluence of 1014 cm−2 were studied. Post-implantation activation annealing was not performed. Test metal–insulator–semiconductor (MIS) structures were created based on as-grown and as-implanted samples by plasma-enhanced atomic layer deposition of Al2O3 insulator films. The admittance of the fabricated MIS structures was measured over a wide range of frequencies and temperatures. When determining the parameters of MIS structures, we used techniques that take into account the presence of near-surface graded-gap layers and series resistance of the HgCdTe film bulk, as well as the high density of slow surface states. It was found that, in as-implanted samples, the donor center concentration in the near-surface layer exceeds 1017 cm−3 and increases with distance from the HgCdTe-Al2O3 interface (at least up to 90 nm). After implantation, the conductivity of MBE HgCdTe film bulk increases markedly. It was shown that, for as-implanted samples, the generation rate of minority charge carriers in the MBE HgCdTe surface layer is significantly reduced, which indicates the appearance of a low defect layer with a thickness of at least 90 nm

Admittance studies of modification of HgCdTe surface properties with ion implantation and thermal annealing

Metal–insulator–semiconductor (MIS) structures based on HgCdTe were fabricated after various stages of p

Admittance of metal-insulator-semiconductor structures based on graded-gap HgCdTe grown by molecular-beam epitaxy on GaAs substrates

Metal–insulator–semiconductor structures based on n-Hg1−xCdxTe (x = 0.19–0.25) were grown by molecular-beam epitaxy on the GaAs (0 1 3) substrates. Near-surface graded-gap layers with high CdTe content were formed on both sides of the epitaxial HgCdTe. Admittance of these structures was studied experimentally in a wide temperature range (8–150) K. It is shown that an increase in the composition of the working layer and a decrease in temperature lead to a decrease in the frequency of transition to high-frequency behavior of the capacitance–voltage characteristics. The differential resistance of space charge region in the strong inversion increases with the composition of the working layer and for x = 0.22 and 0.25, the differential resistance is limited by the Shockley-Read generation. The values of the differential resistance of space charge region at different frequencies and temperatures were found

Electrical characterization of insulator-semiconductor systems based on graded band gap MBE HgCdTe with atomic layer deposited Al2O3 films for infrared detector passivation

The electrical properties of MIS structures based on graded band gap Hg0.77Cd0.23Te grown by the molecular beam epitaxy method with the Al2O3 dielectric formed by the plasma enhanced atomic layer deposition method were investigated. It is established that for such structures the recharge of slow states takes place and significantly distorts the form of the capacitance-voltage (C-V) characteristics. A technique is proposed for constructing the C-V curves of HgCdTe MIS structures, which makes it possible to eliminate the effect of slow surface states. It is shown that Al2O3 films are suitable for passivation of infrared detectors due to small flat band voltages leading to the realization of the depletion or weak inversion modes. The hysteresis of electrical characteristics is eliminated when an intermediate CdTe layer with a thickness of about 0.2 μm is grown in situ during the epitaxial growth

Investigation of the effect of thermal annealing on the electrical properties of the near-surface layer of MBE n-HgCdTe using MIS techniques

Heteroepitaxial n-Hg0.78Cd0.22Te films with near-surface graded-gap layer