- A semiconductor is doped with ND (ND >> ni) and has resistance R1. The same semiconductor is then doped with the unknown amount of acceptors NA(NA>>ND), yielding a resistance of 0.5R1. Find NA in terms of ND if Dn/Dp =50
- Assume that in an n-type semiconductor at T = 300K, the electron concentration varies linearly from 1*1018 to 7*1017/cm3 over a distance of 0.1 cm. Calculate the diffusion current density if electron diffusion coefficient is Dn = 22.5 cm2/s
- Minority carriers (holes) are injected into a homogenous n-type semiconductor sample at a point. An electric field of 50V/cm is applied across the sample and the field moves these minority carriers a distance of 1cm in 100 µs. Find the drift velocity and diffusivity of the minority carriers.
- Find the resistivity at 300 K for a silicon sample doped with 1.0x 1014 per cm3 of phosphorous atoms, 8.5 * 1012 cm-3 of Arsenic atoms, and 1.2 * 1013 cm-3 of boron atoms. Assume that the impurities are completely ionized and the mobility are µn = 1500 cm2/V-s, and µp= 500 cm2/V-s, independent of impurity concentrations.
- A semiconductor has a resistivity of 1.0 ohm-cm, and a Hall coefficient of -1250cm2/C. Calculate the carrier density and mobility, assuming that only one type of carrier is present and the mean free time is proportional to the carrier energy i.e. Γ is directly proportional to E.
References
Q1 Q2 Q3 Q4 Q6 Q7 Q8 – “Semiconductor devices Physics and Technology” by SM Sze
Q5 – “Solid State Electronic Devices” by Ben Streetman and Sanjay Banerjee
Q9 Q10 – “ Physics of Semiconductor Devices” by SM Sze, Kwok Ng.
Graphs – “http://ecee.colorado.edu/~bart"