Sign up now
to enroll in courses, follow best educators, interact with the community and track your progress.
Download
GATE-2009 One Mark Question and Solutions (Electronic Devices)
340 plays

More
Specially designed for GATE EC Aspirants  Covers previous 10 years (2009-2018) 1 mark questions of Electronic Devices  Detailed solution provided  Related concept has been also explained

Akhilesh PANDEY
B.Tech. in EC, GATE 2017 AIR 18, YouTuber (channel name - STUDENT MODULATOR), 5 years Teaching Experience

Unacademy user
  1. Previous 10 Years (2009-18) 1 Mark Que.&Sol Subject: Electronic Devices Year: 2009 By- AKHILESH PANDEY


  2. About Me B. Tech. in Electronics & Communication GATE 2017 AIR 18 (EC) 5 Years Teaching Experience > Youtuber (channel- STUDENT MODULATOR)


  3. Course Overview Specially designed for GATE EC Covers previous 10 years (2009-2018) 1 mark questions of Electronic Devices Detailed solution provided Related concept has been also explained Aspirants


  4. Q.1 In an n-type silicon crystal at room temperature, which of the following can havea concentration of 4 x 1019 cm-3? (A) Silicon atoms (B) Holes (C) Dopant atoms (D) Valence electrons


  5. Sol. 1 At room temperature for silicon crystal, we have Concentration of Silicon 5 x 1022 atoms/cm3 intrinsic carrier concentration (holes or electrons) = 1.5 1010 cm i.e. only 1 atom in about 1012 contributes a free electron (and also a hole) to the silicon crystal because of broken covalent bonds. When silicon is doped with donor atoms, n-type silicon is formed.


  6. In n-type silicon, Concentration of Silicon atoms will be same as intrinsic silicon, i.e. Concentration of Silicon 5 x 1022 atoms/cm3 > As number of holes decreases due to doping of donor atoms, Concentration of holes < 1.5 1010 cm-3 Concentration of dopant atoms can have any value. > Since, each silicon atom consists 4 valence electrons, so concentration of valence electrons will be of the same order of concentration of donor atoms, i.e. Concentration of valence electrons ~ 5 1022 /cm So, the given concentration 4 x 1019 cm3 can be of donor atom


  7. Q.2 The ratio of the mobility to the diffusion coefficient in a semiconductor has the units (A) V-1 (B) cm V-1 (C) V cm-1 (D) V S


  8. Sol.2 For semiconductor, the relation between diffusion coefficient and mobility is expressed as D kT where D diffusion coefficient mobility, VT=Thermal voltage As we have to find the unit for ratio of mobility to the diffusion coefficient, so we have Unit of V (i.e., Thermal voltage) is volt. Hence, unit ofwl be V-1


  9. Thank You Rate Review Recommend Follow My Lectures on Unacademy akhilesh.pandey