Investigation on performance enhancement of micro-sized IR photodetectors

As an Infrared detector with high responsivity, high transmission speed, and low dark current, InP/InGaAs p-i-n photodetectors (PD) have been used as a promising technology for many applications, including optical communication and various imaging applications, for over two decades. In the following optoelectronic devices scaling down, such as micro-sized light-emitting diodes (LEDs), the integration of PDs in micro-sizes may find a more important position in the near future. Device size shrinkage would be essential to achieve a low dark current and a low depletion capacitance. However, the biggest technical challenge with the conventional micro-size p-i-n detector is producing a significant dark current due to surface recombination. The increased surface area to volume ratio leads to a high carrier surface recombination rate, which significantly degrades the performance of InP-InGaAs micro-sized PDs, including the responsivity and detectivity. In this case, the most important parameter affecting device performance is the surface recombination velocity (SRV), reflecting the impact of surface recombination rate, depending majorly on the etching process and the passivation layer quality. This thesis investigates the size-dependent properties of the micro-sized PDs, such as dark current, capacitance, and responsivity. In this work, the simulation tool Atlas SILVACO is employed to simulate the optoelectrical properties of the devices and Finite Difference Time Domain (FDTD) for the optical simulation. The simulation results show that the responsivity of micro-sized PDs decreases from 80% to 15% when the size shrinks down from 100 μm to 10 μm. To suppress this performance degradation, we went through two different investigation routes. First of all, we studied two different top surface configurations to couple more light into the micro-sized PDs. Both optical and optoelectrical simulations showed that the configuration with one-sided contact improves the generation rate, reflectivity, and responsivity by ~33%. Secondly, we scrutinized the enhancement of the gating technique in the performance of the micro-sized PDs. By changing the surface potential and electron concentration at sidewalls, this technique helps to decrease the dark current density in reverse gate biases. The increment of this method for external quantum efficiency (EQE) was ~18%

Spatial Analysis of The Effects of Distributive Justice Indices on Rural Areas Resilience to Drought (Case Study: Rural Areas in West of Urmia Lake)

Due to a better understanding of the status of resilience and optimal management of distribution services, it will be essential to analysis of spatial resilience patterns and examine the spatial relationships between resilience and influencing factors, including distributive justice. Therefore, the purpose of this descriptive-analytical study is to investigate distributive justice and its effect on the resilience of villages west of Lake Urmia to drought. The statistical population of the present study was all villages located within 10 km of the shore of Lake Urmia, which were selected 53 villages as a research environment and finally 380 households as the human analysis units using the Cochran's formula and by multi-stage random sampling method. The research instrument was a researcher-made questionnaire whose validity and reliability were confirmed using Cronbach's alpha coefficient. In this study, the effective factors (distributive justice indices) on the resilience of the studied villages were investigated by geographic weighted regression (GWR). The results of GWR regression showed that the variables entered in the model explain 47.8% of the dependent variable. Also, the results of regression model (OLS) showed that infrastructure, trade-service and economic indicators have the greatest impact on the resilience to drought in the studied villages

Analysis of Key Drivers Affecting the Acceptance of Community-based Tourism in Rural Settlements with a Futuristic Approach (Case Study: Shirvan County)

Therefore, the aim of the present study is to identify and analyze the key factors and main drivers on the acceptance of community-based tourism in rural settlements of Shirvan county. The research method of this research is applied and based on its nature; it is descriptive-analytical. The information has been collected by documentary and field methods. The questionnaire for extracting key drivers affecting the formation of community-based tourism in rural settlements of Shirvan county has been prepared in the form of a micro-Mac questionnaire and has been distributed and completed among community members. 11 questionnaires were considered for rural experts and relevant organs. Micmac software was used to analyze the data and structurally analyze the effectiveness of each of the indicators affecting the formation of community-based tourism in rural areas. The results showed that due to the high score of direct and indirect impact, 16 factors were identified in 4 main groups of key drivers in the future of tourism development of rural settlements of Shirvan county, which factors:)2+) Indirect (961+), overall visitor satisfaction of tourist attractions and ranking according to the purpose of direct (2+) indirect visit (487+), diversity of investors in the tourism sector and increase of non-governmental investments in the direct village (1 +) Indirect (513+), suitable tourism climate, the existence of beautiful, amazing and unique landscapes and rich pastures and a variety of medicinal and edible plants, (1 +) indirect (297+) are the most important factors

Explanation of the Impact Scenarios of the Smart Growth Approach on the Sustainability of Rural Settlements (Case Study: Jiroft County)

In the current research, with the participation of managers, officials and academic experts, key drivers affecting the smart growth of rural settlements in Jiroft County have been identified and finally, scenarios effective on the formation of smart growth of rural settlements have been formulated. The research is applied in terms of purpose and descriptive-analytical in terms of research method. The method of collecting data and information was in the form of library and documents and survey (interview). By examining scientific sources, 57 factors influencing the smart growth of rural settlements were identified, which were categorized into 4 dimensions; And a total of 30 people, including managers of related organizations and academic experts, were interviewed. Data analysis was based on prospective research techniques; including structure analysis, interaction analysis (Micmac and Scenario Wizard software). The results showed that there are 35 scenarios with weak compatibility and only one scenario is in a state of strong and stable compatibility (zero incompatibility). The first scenario, which is a scenario with a positive direction, has a total interaction score of 446 and a compatibility value of 5; While the second scenario, which is the unfavorable scenario, has a total interaction effect score of -93 and a compatibility value of -1. The third scenario (standing) also had a compatibility value of 3, and with a total score of 42 interactions, it can be one of the possible scenarios for the future of rural physical-spatial developments

Seed Transmission of Beet Curly Top Virus and Beet Curly Top Iran Virus in a Local Cultivar of Petunia in Iran

Beet curly top virus (BCTV) and beet curly top Iran virus (BCTIV) are known as the causal agents of curly top disease in beet and several other dicotyledonous plants in Iran. These viruses are transmitted by Circulifer species, and until now, there has been no confirmed report of their seed transmission. A percentage (38.2–78.0%) of the seedlings developed from the seeds of a petunia local cultivar under insect-free conditions showed stunting, interveinal chlorosis, leaf curling, and vein swelling symptoms, and were infected by BCTV when tested by PCR. Presence of BCTV in seed extracts of petunia local cultivar was confirmed by PCR and IC-PCR, followed by sequencing. Agroinoculation of curly top free petunia plants with a BCTV infectious clone resulted in BCTV infection of plants and their developed seeds. These results show the seed infection and transmission of BCTV in a local cultivar of petunia. Similar experiments performed with BCTIV showed that this virus is also seed transmissible in the same cultivar of petunia, although with a lower rate (8.8–18.5%). Seed transmission of curly top viruses may have significant implications in the epidemiology of these viruses

Reduction of Phenmedipham + Desmedipham + Ethofumesate Herbicides Dosage Based on Application Timing in Sugar Beet

An experiment was conducted to study possible reduction of concentration (dose) of phenmedipham + desmedipham + ethofumesate herbicides at different application times to control weeds in sugar beet field. Thus, a factorial experiment based on complete randomized block design with three replications was performed at Sabzevar, Khorasan-e-Razavi in 2013. Factors consisted of herbicide dosages (control, 75% of the recommended dosage, and 125% of recommended dosage and application times at 2-4, 4-8 and 8-12 leaf stages of sugar beet. Herbicide used in the experiment was phenmedipham (9.2%) + desmedipham (7.2%) + ethofumesate (11.3%) (PROGRESS OF BETAMIX) as 877 ga.i ha-1 27.4 EC. The results indicated that the delayed application of herbicide increased weed density by 55.92% and weed dry matter by 33%. Application of herbicide at 4-8 leaf stage produced highest root and sugar yields. Root impurities were not affected by the time of herbicide application. Used of 125% of recommended dosage resulted in lowest weed density and weed dry matter and highest root and sugar yields. Impure sugar percentage and K content was not affected by herbicide dosage. Other root quality characteristics were not statistically significant different between the recommended dose 125% of recommended dosages. Results as a wholes suggested that at early growth stage of sugar beet (2-4 leaf stage) lower herbicide dosage and at later growth stage of sugar beet (8-12 leaf stage) higher herbicide dosage may produce highest root yield of sugar beet

Factors Affecting the Formation of Shadow Economy (Importation of Goods) in Rural Areas of Iran

The economic situation of every village is affiliated to the function of the existing economic sectors in the village (agriculture, industry, services). This article is derived from the field study (case study) in villages in the central part of the Lamerd in the southern province of Fars, in terms of nature, is a kind of exploratory investigation and benefiting from scientific methodologies and using a questionnaire and interview, seeks to find a reasonable solution and answer why and how to expand the formation and activity and its effect on the process of development in the villages of the study. Volume of the sample, according to Cochrane, including 156 families who have been chosen by random sampling method. Results show that the main factors which caused the emergence of this kind of employment and increasing prosperity in the region, can be key factors, including the former and current migration of the inhabitants of the  region, to the Persian Gulf countries and high revenues from the employment of  people in those countries, appropriate spatial- regional location appropriate access roads and transit routes and the proximity to the south of the country 's booming country and commercial, including Assalouyeh Ports, Bandar Abbas and Bushehr pointed out

A spatial assessment of the infrastructure resilience capacity in rural communities of Bojnourd County by FAHP model and fuzzy logic in GIS

The main purpose of the present study is to assess the relationship between environmental vulnerability and infrastructure resilience of rural communities (in Bojnourd County), so that one can improve the resilience capacity in rural areas. The research was conducted in a descriptive-analytical method and in nature it is applicable in local planning and rural development systems. Research variables have been selected after reviewing theoretical foundations and literature on vulnerability and resilience assessment in Iran and other countries. Accordingly, two general indicators of vulnerability assessment and infrastructure resilience of rural communities were developed using 26 criteria in FAHP and fuzzy logic (Gamma operator with the thresholds of 0.7, 0.8 and 0.9) in the GIS environment. The results indicate that approximately 56.69% of the County’s area has a high and very high environmental vulnerability, and 47 villages were situated in this area. The survey of the resilience index indicates that there is a significant and direct relationship between low resilience in rural areas and environmental vulnerabilities in the eastern, southern and northeastern parts of Bojnourd County. In addition, based on the FAHP output, about 31 percent of the rural areas of the county, and based on the output of fuzzy logic, about 53 percent of the rural areas of the county are in a very high resilience level). The analysis of the output results of FAHP and fuzzy logic in GIS with a Kappa coefficient of 0.166 showed that the results of the two models have comparatively weak but direct correlation, which was determined by measuring the accuracy of the models using ground control points. Fuzzy logic model with a Kappa coefficient of 0.772 is more accurate than the FAHP model with a Kappa coefficient of 0.550