1
GATE ECE 2015 Set 2
Numerical
+2
-0
A dc voltage of 10V is applied across an n–type silicon bar having a rectangular cross–section and a length of 1cm as shown in figure. The donor doping concentration ND and the mobility of electrons $$\mu$$n are $$10^{16}$$ cm-3 and 1000 cm2 V-1s-1, respectively. The average time (in $$\mu$$s) taken by the electrons to move from one end of the bar to other end is _______________. 2
GATE ECE 2014 Set 4
Numerical
+2
-0
Consider a silicon sample doped with ND = 1×1015/cm3 donor atoms. Assume that the intrinsic carrier concentration ni = 1.5×1010/cm3. If the sample is additionally doped with NA = 1×1018/cm3 acceptor atoms, the approximate number of electrons/cm3 in the sample, at T=300 K, will be _________________.
3
GATE ECE 2014 Set 4
+2
-0.6
An N-type semiconductor having uniform doping is biased as shown in the figure. If EC is the lowest energy level of the conduction band, EV is the highest energy level of the valance band and EF is the Fermi level, which one of the following represents the energy band diagram for the biased N-type semiconductor?

A B C D 4
GATE ECE 2014 Set 2
Numerical
+2
-0
Assume electronic charge q = 1.6×10-19 C, kT/q = 25 mV and electron mobility μn = 1000 cm2/V-s. If the concentration gradient of electrons injected into a P-type silicon sample is 1×1021/cm4, the magnitude of electron diffusion current density (in A/cm2) is _________.
GATE ECE Subjects
Signals and Systems
Network Theory
Control Systems
Digital Circuits
General Aptitude
Electronic Devices and VLSI
Analog Circuits
Engineering Mathematics
Microprocessors
Communications
Electromagnetics
EXAM MAP
Joint Entrance Examination