Electrical properties of transparent and conducting Ga doped ZnO

Journal ArticleIn this paper, we report on the metal-semiconductor transition behavior observed in transparent and conducting ZnO:Ga films grown by pulsed-laser deposition. The electrical resistivity measurements were carried out on ZnO films with varying Ga concentration in the temperature range of 14 to 300 K. The electrical properties were correlated with film structure, and detailed structural characterization was performed using x-ray diffraction, transmission electron microscopy, and x-ray photoelectron spectroscopy. The room-temperature resistivity of these films was found to decrease with Ga concentration up to 5% Ga, and then increase. The lowest value of resistivity (1.4 x 10−4 Ω cm) was found at 5% Ga. Temperature dependent resistivity measurements showed a metal-semiconductor transition, which is rationalized by localization of degenerate electrons. A linear variation of conductivity with √T below the transition temperature suggests that the degenerate electrons are in a weak-localization regime. It was also found that the transition temperature is dependent on the Ga concentration and is related to the increase in disorder induced by dopant addition. The results of this research help to understand the additional effects of dopant addition on transport characteristics of transparent conducting oxides (TCOs) and are critical to further improvement and optimization of TCO properties

Epitaxial growth and properties of MoOx(2<x<2.75) films

Journal ArticleWe report the growth of epitaxial molybdenum oxide (MoOx,2<x<2.75) films on c plane of sapphire substrate using pulsed laser deposition in oxygen environment. The structure was characterized using x-ray diffraction, high resolution transmission electron microscopy and x-ray photoelectron spectroscopy (XPS). Electrical resistivity and optical properties were investigated using four-point-probe resistivity measurements and spectroscopy techniques, respectively. It was found that the film had a monoclinic structure based on MoO2 phase and showed an unusual combination of high conductivity and high transmittance in the visible region after annealing. The unusual combination of these properties was realized by systematically controlling the relative fraction of different oxidation states of molybdenum, namely Mo4+, Mo5+, and Mo6+ in the monoclinic phase. For a film 60 nm thick and annealed at 250 °C for 1 h, the ratio of Mo6+ / (Mo4++Mo5+) was determined to be ~2.9/1 using XPS, and a typical value of transmittance was ~65% and resistivity close to 1310−3 Ω cm. These results demonstrate growth of epitaxial MoOx films with tunable electrical and optical properties. Further optimization of these properties is expected to result in applications related to display panels, solar cells, chromogenic (photochromic, electrochromic, gasochromic) devices, and transparent conducting oxides. Our ability to grow epitaxial MoOx films can further aid their integration with optoelectronic and photonic devices

Metallic conductivity and metal-semiconductor transition in Ga-doped ZnO

Journal ArticleThis letter reports the metallic conductivity in Ga:ZnO system at room temperature and a metal-semiconductor transition (MST) behavior at low temperatures. Zn0.95Ga0.05O films, deposited by pulsed laser deposition in the pressure range of ~10−2 Torr of oxygen, were found to be crystalline and exhibited degeneracy at room temperature with the electrical resistivity close to 1.4x 10−4 Ω cm and transmittance > 80% in the visible region. Temperature dependent resistivity measurements of these highly conducting and transparent films also showed, for the first time, a MST at ~170 K. Mechanisms responsible for these observations are discussed in the terms of dopant addition and its effect on ionization efficiency of oxygen vacancies

Ferromagnetism in Co doped CeO2: observation of giant magnetic moment with a high Curie temperature

Journal ArticleWe report room temperature ferromagnetism in single crystal Ce1−xCoxO2−δ (x≤0.05) films deposited on a LaAlO3(001) substrate. Films were grown by a pulsed laser deposition technique and were thoroughly characterized using x-ray diffraction, high-resolution transmission electron microscopy coupled with electron energy loss spectroscopy and scanning transmission electron microscopy-Z contrast, x-ray photoelectron spectroscopy, optical transmission spectroscopy, and magnetic measurements. These films are transparent in the visible regime and exhibit a very high Curie temperature ~740-875 K with a giant magnetic moment. Our results indicate that the ferromagnetic property is intrinsic to the CeO2 system and is not a result of any secondary magnetic phase or cluster formation

Stabilisation of Deep Soil Cut Using Micropiles and Soil Nailing

The Railway route through south-west part of India (Konkan Railway) is passing through a hilly terrain. The route is developed by cutting the mountains in slopes and construction of tunnels. Many slopes along this route are very deep and steep. The region is characterized by lateritic soil. A heavy monsoon initiates some of the deep slope failures resulting in large magnitude of loss – both in money and life. The initial failure of one of the slope at Chainage 344/900 Km was stabilized by Gabion walls. West side of the Soil cutting was about 100 m long and a lateritic hilly slope steeply rises to 20 m above the track level at the collapse location. Initially the cutting line was 15m away from external track edge. However, after the heavy monsoon in June 2000, the soil slope collapses causing the lateral movement of the gabion wall and lateral shifting of the nearby railway track. The investigation was carried out to study the failure. The scheme of combination of conventional Soil Nails and Micropiles in addition to Gabion wall was proposed. The scheme was executed in Jan 2001 to May 2001. Load Tests were performed on Micropiles and Nails to verify the design. The slope is successfully stable for last 10 years

Ethnomedical Knowledge of Plants used by the Tribal people of Purandhar in Maharashtra, India

This study presents the results of a field survey of the plants used medically by the tribal people of Purandhar in Maharashtra, India. Tribes like Dhangars and Gowlis inhabit the dry deciduous forests of the region. This is an effort to record the valuable ethnomedical knowledge of these Purandhar tribes. A total of 77 species belonging to 30 families and 56 genera were included. These plants are used to treat various aliments, discomforts and diseases like whooping cough, asthma, diabetes, diphtheria, conjunctivitis, snake bite, scorpion bite, etc

Pulsed Current-Mode Supply of Dielectric Barrier Discharge Excilamps for the Control of the Radiated Ultraviolet Power

UV excimer lamps are efficient narrowband sources of UV radiation with applications in various domains. The issue of controlling the UV emission by means of the power supply associated with such lamps favors pulsed current-controlled generators. After having established the previous statements, we propose a dedicated power converter topology which implements the needed performances. The analysis of the degrees of freedom of this structure shows the capability of this pulsed supply to realize the control of both the pulses’ current energy and of the mean power transferred to the lamp. Actual experimental realizations and measurement are presented and the feasibility and the performances of the proposed solutions are established

Genetic Divergence for Yield, Physiological and Quality Traits in Super-Early Pigeon pea (Cajanus cajan. (l.) Millsp.)

The present investigation aimed to study genetic divergence and clustering pattern of 37super-early pigeon pea genotypes. Analysis of variance and hierarchical cluster analysis of tocher’s method revealed significant differences among the genotypes for all the traits under study. Based on genetic distance (D2 value), the 37 genotypes were grouped into 9 distinctive clusters, of which cluster I and II formed the largest clusters with 10 genotypes in each. Among all the characters understudy, leaf area index(LAI) at 60 DAS contributed more to the divergence followed by leaf area (17.02) and leaf area index (12.71) at maturity. Based on the average inter-cluster distance, the cluster III and IX (66.93) tailed by cluster III and VIII (64.86) and cluster VI and VIII (64.06) showed higher inter-cluster distance depicting the wider divergence. Trait-wise selection of diverse parents from the above clusters aids in exploitation of heterosis in superearly pigeon pea

Genetic Variability for Yield, Physiological and Quality Traits in Novel Super-Early Pigeonpea (Cajanus cajan (L.) Millsp.)

Super-early pigeonpea are novel genotypes that are reported to be photoperiod insensitive making it possible to grow it in non-traditional regions. Estimation of genetic parameters would be useful in developing appropriate selection and breeding strategies. A study was conducted to evaluate 37 super-early pigeonpea genotypes to access the magnitude of variability and to study heritable component of variation present in the yield, physiological and quality traits. The results revealed that traits leaf area duration between 60 DAS & maturity followed by leaf area & leaf area index at maturity, net assimilation between 60 DAS & maturity, leaf area index & leaf area at 60 DAS, leaf area duration between 60 DAS & maturity and plant height had high had higher PCV and GCV values. In general, phenotypic coefficients of variation (PCV) estimates were higher than genotypic coefficients of variation (GCV) estimates for all the characters under study, but the difference was relatively small indicating that these characters were less influenced by the environment and selection to improve those traits might be effective. High heritability combined with high genetic advance as a percent of mean was noted for all the traits except protein content conveying the governance of additive gene on trait expression. Anticipating these traits as selection index reaps competent improvement in yield, physiological and quality traits in early maturing pigeonpea

Study of CGMS based Short Duration Hybrids of Pigeonpea [Cajanus cajan (L.) Millsp.] In Terms of Heterosis

Twenty seven pigeonpea [Cajanus cajan (L.) Millsp.] hybrids were developed by hand pollination using three CMS lines (A lines) and nine testers (R lines). These hybrids along with their parents and two standard checks (VL Arhar1 and ICPL 161) were evaluated in a randomized block design with three replications during kharif 2016-17 for the heterosis studies. Results indicated that the crosses ICPA 2039 x ICPL161 and ICPA 2039 x ICPL 90048 had manifested significant heterobeltiosis and standard heterosis over two checks viz., VL Arhar1 and ICPL 161 for grain yield per plant and yield contributing characters. The stability of these promising crosses can be studied across the different environments and feasibility for their commercial utilisation could be tested in further generations