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PIB 7th May


  1. Scientists fabricate energy-efficient photodetector
  2. Environment Impact Assessment Notification(EIA), 2020
  3. Modifications in PMRF Scheme


Focus: GS-III Science and Technology

Why in news?

Scientists from Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), autonomous institute under the Department of Science and Technology, have fabricated an economical and energy-efficient wafer-scale photodetector (thin slice-based) using gold – silicon interface, for security applications. It could help detect weak scattered light as an indication of unwanted activity.


  • Photodetectors are the heart of any optoelectronic circuit that can detect light and are employed for a wide variety of applications ranging from controlling automatic lighting in supermarkets to detecting radiation from outer galaxy as well as security-related applications.  
  • However, the material cost and the intricate fabrication processes involved in realizing high-performance detectors make them unaffordable for day to day applications. 
  • The scientists have fabricated gold (Au)– silicon (n-Si) interface, which showed high sensitivity towards light demonstrating the photodetection action.  
  • The Au–Si interface was brought about by galvanic deposition, a technique for electroplating of metals, wherein water-based solutions (electrolytes) are used, which contain the metals to be deposited as ions.  
  • In addition, a nanostructured Au film also was deposited on top of p-type silicide (having an excess of positive charges), which acts as a charge collector. 
  • The detector exhibits a rapid response of 40microseconds and can detect low light intensities. The device covers a broad spectral range from Ultraviolet to Infrared. 
  • Besides, it shows excellent uniformity throughout the entire active area with less than 5% variation in response. 

What is a Photodetector?

  • Photodetectors, also called photosensors, are sensors of light or other electromagnetic radiation.  
  • A photo detector has a p–n junction that converts light photons into current.  
  • The absorbed photons make electron–hole pairs in the depletion region.  
  • Photodiodes and photo transistors are a few examples of photo detectors. Solar cells convert some of the light energy absorbed into electrical energy. 
  • Other optical devices similar to photo detectors are solar cells which also absorb light and turn it into energy.  
  • A similar but different optical device is the LED which is basically the inverse of a photodiode, instead of converting light to a voltage or current, it converts a voltage or current to light.

Applications of Photo Detectors 

  1. Photo detectors are used in various different applications such as radiation detection, smoke detection, flame detection and to switch on relays for street lighting.
  2. The circuits that use photodiodes use either normally closed or normally open contacts depending on the desired operation.
  3. In a smoke detector circuit the photo diode is attached to a relay switch, this switch is normally closed and attached to the fire alarm. When the photo diode conducts it picks up the relay switch, this causes the normally closed switch to open preventing the alarm from activating. When the photo diode fails to conduct, the normally closed contact activates the alarm.
  4. Photo diodes are also used in modern oil burning furnaces as a safety feature. The photo diode is comprised of lead sulphide and is used to detect the flame from the boiler, in the event that the flame goes out or fails to occur the photo diode opens the circuit, cutting power to the motor and step up transformer.
  5. Another commonly used application is street lights. The photo diode in the circuit uses switch-on relays to turn on the street lights when the diode fails to conduct and turns the lights off with when sufficient light is present.
  6. Photodiodes are also used with lasers to form security system. When the light projected by a laser to the photodiode is broken a security alarm is tripped.


Focus: GS-III Environment and Ecology

Why in news?

 Notice period for draft Environment Impact Assessment Notification(EIA), 2020 is extended till 30th June.

What is Environment Impact Assessment?

  • Environmental Impact Assessment (EIA) is a process of evaluating the likely environmental impacts of a proposed project or development, taking into account inter-related socio-economic, cultural and human-health impacts, both beneficial and adverse.
  • UNEP defines Environmental Impact Assessment (EIA) as a tool used to identify the environmental, social and economic impacts of a project prior to decision-making.
  • It aims to predict environmental impacts at an early stage in project planning and design, find ways and means to reduce adverse impacts, shape projects to suit the local environment and present the predictions and options to decision-makers.
  • Environment Impact Assessment in India is statutorily backed by the Environment Protection Act, 1986 which contains various provisions on EIA methodology and process.

Stages of Environment Impact Assessment:

  • Project screening: This entails the application of EIA to those projects that may have significant environmental impacts.
  • Scoping: This step seeks to identify, at an early stage, the key, significant environmental issues from among a host of possible impacts of a project and all the available alternatives.
  • Consideration of alternatives
  • Description of the project/development action: This step seeks to clarify the purpose and rationale of the project and understand its various characteristics, including the stages of development, location and processes.
  • Description of the environmental baseline: This includes the establishment of both the present and future state of the environment, in the absence of the project, taking into account the changes resulting from natural events and from other human activities.
  • The prediction of impacts: This step aims to identify the likely magnitude of the change (i.e., impact) in the environment when the project is implemented in comparison with the situation when the project is not carried out.
  • Evaluation and assessment of significance: This seeks to assess the relative significance of the predicted impacts to allow a focus on key adverse impacts.
  • Mitigation: This involves the introduction of measures to avoid, reduce, remedy or compensate for any significant adverse impacts.
  • Public consultation and participation: This aims to assure the quality, comprehensiveness and effectiveness of the EIA, as well as to ensure that the public’s views are adequately taken into consideration in the decision-making process.
  • EIS presentation: This is a vital step in the process. If done badly, much good work in the EIA may be negated.
  • Review: This involves a systematic appraisal of the quality of the EIS, as a contribution to the decision-making process.
  • Decision-making:
  • Post-decision monitoring: This involves the recording of outcomes associated with development impacts, after the decision to proceed with the project.

Expert Appraisal Committee (EAC)

The EAC is a multidisciplinary sectoral appraisal committee comprising of various subject matter experts for appraisal of sector-specific projects. The EAC is the recommendatory body. Based on the recommendations of the Expert Appraisal Committee, environmental clearance is accorded or rejected to the project by MoEF&CC.

After 2006 Amendment the EIA cycle comprises of four stages:

  1. Screening
  2. Scoping
  3. Public hearing
  4. Appraisal
  • Category A projects require mandatory environmental clearance and thus they do not undergo the screening process.
  • Category B projects undergoes screening process and they are classified into two types.
  • Category B1 projects (Mandatorily requires EIA).
  • Category B2 projects (Do not require EIA).

Thus, Category A projects and Category B, projects undergo the complete EIA process whereas Category B2 projects are excluded from complete EIA process.

Importance of Environment Impact Assessment:

  • Reduced cost and time of project implementation and design,
    • Avoided treatment/clean-up costs and impacts of laws and regulations.
    • Lays base for environmentally sound projects;
    • Greater awareness of environmental legislation;
    • Protection of Environment
    • Optimum utilization of resources(balance between development and Environmental protection)


Focus: GS-III Science and Technology

Why in news?

Union Human Resource Development Minister announced that, to boost research in the country various amendments have been carried out in Prime Minister’s Research Fellowship (PMRF) Scheme.


  • After the amendments, now for the students from any recognised institute/ university (other than IISc/ IITs/NITs/IISERs/IIEST/CF IIITs), the requirement of GATE Score is reduced to 650 from 750 apart from minimum CGPA of 8 or equivalent.
  • Now there will be two channels of entries, one direct entry and lateral entry. In lateral entry, the students, who are pursuing PhD in PMRF granting institutions (completed 12 months or 24 months as per certain requirements) can also apply to become fellow under the scheme as per new guidelines.
  • NITs, which appear in top 25 institutions as per NIRF Ranking (overall) can also become PMRF Granting institution.

What is the purpose of these changes?

  • These modifications will enable more students to avail of the benefit under the Prime Minister’s Research Fellowship Scheme.
  • To boost research a dedicated Division is being created in the ministry with the name of “Research and Innovation Division”.

What is PMRF Scheme?

  • In 2018, Prime Minister’s Research Fellows (PMRF) Scheme was launched to offer direct admission to such students in the Ph.D programmes in IITs, IISERs and IISc and attract meritorious students into research.
  • This scheme is aimed at attracting the talent pool of the country to doctoral (Ph.D.) programs of Indian Institutes of Technology (IITs) and Indian Institute of Science (IISc) for carrying out research in cutting edge science and technology domains, with focus on national priorities.
  • PMRF Scheme has been designed for improving the quality of research in various higher educational institutions in the country.
  • The selection process for the PMRF will be a rigorous two stage process with screening by the Reviewers and final selection by the Selection Committee for each broad discipline to ensure selection of the best talent.
  • Admission under the PMRF will be made in 18 broad disciplines. For each broad discipline one IIT or IISc (Nodal Institute) will coordinate the admission process.

The PMRF Scheme provides:

  • A fellowship of Rs.70,000/- per month for the first two years, Rs.75,000/- per month for the 3rd year, and Rs.80,000/- per month in the 4th and 5th year.
  • A research grant of Rs.2.00 lakh per year will be provided to each of the Fellows for a period of 5 years to cover their academic contingency expenses and for foreign/national travel expenses.
December 2023