Search

Ge/Si(001) heteroepitaxial layers were grown by HW CVD and in situ doped with Ga or Sb using a separate resistively heated Ge source containing one of these impurities. Sublimation of the germanium source gave a concentration of ~1 × 1019 cm–3 gallium atoms in the layers. The mode of introduction of this impurity into the epitaxial layers was investigated as a function of hot filament (Ta) temperature and growth temperature using C–V and Hall effect. To increase the maximum concentration of charge carriers in the Ge/Si(001) layers, a melt zone was formed on the Ge source during the growth of the layers, which made it possible to increase the concentration of impurities in the Ge layer by almost an order of magnitude. [ABSTRACT FROM AUTHOR]

The results of experimental studies of processes of the radiation defect formation under ion implantation of narrow-gap CdxHg1-xTe solid solutions (MCT) are presented. The processes of formation of structural damages of the crystal and their effect on the electrophysical properties of ion-implanted bulk crystals and ptype heteroepitaxial structures grown by liquid-phase and molecular-beam epitaxy are considered. The results on the spatial distribution of implanted boron atoms and radiation donor centers in these materials are presented as a function of the mass, dose, and energy of ions being implanted and the implantation temperature. The processes and models of the formation of n+-n--p-structures during boron ion implantation in p-type MCT and their experimental proof are considered. [ABSTRACT FROM AUTHOR]

Processes of formation of n-n-p-structures in boron-implanted heteroepitaxial (HEL) CdHgTe (CMT) layers of p-type grown by molecular beam epitaxy (HEL CMT MBE) with different compositions of the upper graded-gap layer are studied. It is shown that the surface composition (x) of HEL CMT MBE significantly affects both the electrical parameters of the implanted layer and the spatial distribution of radiation defects of donor type. For HEL CMT MBE with the small surface composition x = 0.22-0.33, it is found that the layer electron concentration (N) is decreased after saturation with accumulation of radiation defects, as the dose of B ions is increased in the range of D = 1⋅10−3⋅10 сm. An increase of the surface composition up to x = 0.49−0.56 results in a significant decrease in N and a disappearance of the saturation of concentration in the whole dose range. The value of N monotonically increases with the energy (E) of boron ions and composition x. It is found that for B-ion energies E = 20−100 keV, the depth of the surface n-layer increases with increasing energy and exceeds the total projected path of boron ions. However, in the energy range E = 100-150 keV, the depth of n-layer stops increasing with the increase of the surface composition. The depth (d) of a lightly doped n-layer monotonically decreases with increasing energy of boron ions in the entire range of E = 20-150 keV. With increasing dose (D) of B ions in the interval D = 1⋅10−1⋅10сm, deep n-layers with d = 4−5 μm are formed only in the HEL CMT MBE with x = 0.22−0.33. For the samples with x = 0.49−0.56, the depth changes in the interval d = 1.5−2.5 μm. At D ≤ 3⋅10сm, n-n-p-structure is not formed for all surface compositions, if implantation is performed at room temperature. However, implantation at T = 130°C leads to the formation of a deep n-layer. Planar photodiodes with the n-p-junction area of А = 35×35 μm made on the basis of the boron implanted HEL CMT MBE with the surface compositions x = 0.33−0.56 had high differential resistance R = 3⋅10−10 Ω∙cm and high product R A = 9.0−20.7 Ω∙cm, where A is the effective area of the charge carrier collecting. The values of R and R A increased with increasing x. It is found that the layer electron concentration in the boron implanted HEL CMT MBE with different surface compositions is increased, when exposed to normal conditions for a few years. [ABSTRACT FROM AUTHOR]

The results of investigations into radiation modification of surfaces of CdHgTe (CMT) heteroepitaxial layers grown by molecular-beam and liquid-phase epitaxy (MBE- and LPE CMT HEL) affected by high-power pulse short-wavelength IR radiation are discussed. It is found that the surfaces of MBE CMT HEL and LPE CMT are enhanced by mercury as a result of high-power pulse short-wavelength IR radiation. [ABSTRACT FROM AUTHOR]

Processes of electrical activation of ion-implanted boron and nitrogen atoms in Cd xHg 1–xTe (CMT) heteroepitaxial layers grown by methods of molecular-beam epitaxy (HEL CMT MBE) and liquid-phase epitaxy (LPE CMT) have been investigated; likewise in bulk crystals of CMT with low-temperature annealings under anodic oxide. The possibility has been demonstrated of using anodic oxide as an efficient mask for postimplantation annealings of p-type HEL CMT MBE in the temperature interval Т = 200–250°C without disruption of the composition of the variband layer or alteration of the electrophysical properties of the structure. It has been established that in HEL CMT MBE the efficiency of activation of boron as a slowly diffusing donor impurity is lowered with growth of the dose of the B + ions and is increased by thermal cycling from Т = 77 K to room temperature. Implanted nitrogen, in contrast to boron, is a rapidly diffusing acceptor impurity in CMT, efficiently compensating both radiation donor centers and activated boron. The degree of electrical activation of nitrogen grows substantially upon thermal cycling. It has been shown that the mobility spectrum is an efficient method for monitoring the process of electrical activation of boron in p-type HEL CMT MBE. Mesa photodiodes based on activated boron in p-type HEL CMT MBE with long-wavelength photosensitivity boundary λ c = 11 μm, prepared here for the first time, had a high maximum value of the product of the differential resistance by the area of the photodiode RdA = (6 − 8)⋅10 2 Ω⋅cm 2, product R0A = 5 − 6 Ω⋅cm 2 (at zero bias), and a diffusion ledge on the inverse branch of the current-voltage ( I– V) characteristic out to a bias voltage of 1.3 V. [ABSTRACT FROM AUTHOR]

The results of measurements of dark current-voltage characteristics of planar diodes of various area produced on the basis of heteroepitaxial MBE p-CMT layers under various modes of boron ion implantation are discussed. It is shown that the diodes with the n/n/p-junction are characterized by far lower dark currents and higher differential resistance Rd as compared with abrupt n-p-junctions. It was experimentally established that the parameter RA, where A is the effective area of minor charge-carrier collection, is more correct that the RA parameter for the n-p-junctions of various areas. [ABSTRACT FROM AUTHOR]

Results of investigations into the electrophysical properties of p- and n-type CdHg-Te heteroepitaxial layers grown by molecular beam and liquid phase epitaxy methods after exposure to high-power pulsed IR radiation of solid-state Nd:YAG and chemical DF lasers at wavelengths of 1.06 and 3.8-4.2 μm, respectively, are presented. It is demonstrated that the main types of defects resulting from pulsed irradiation are mercury vacancies that play the role of acceptors in this material. The spatial distribution of generated mercury vacancies depends on the intensity and wavelength of laser radiation: the defects generated by pulses of the Nd:YAG laser are concentrated only near the surface, whereas DF-laser radiation creates defects in the entire volume of the heteroepitaxial structures. It is established that irradiation with the Nd:YAG laser of the p-CdHg-Te heteroepitaxial layers implanted by boron ions leads to the activation of implanted boron atoms as a result of melting and recrystallization of the irradiated surface layer. [ABSTRACT FROM AUTHOR]