QUESTION: 1 Silicon at T=300K contains a acceptor impurity concentration at Na=1016 cm-3. Determine the concentration of donor impurity atoms that must be added so that the silicon is n-type and the Fermi energy is 0.20eV below the conduction band edge. [Take NC=2.8 x 1019cm ). QUESTION: Two semiconductor materials have exactly the same properties except that material A has a band gap energy of 1.0eV and material B has a band gap energy of 1.2eV. Determine the ratio of n; of material A to that of material B for T=300K. QUESTION:3 A special semiconductor material is to be "designed". The semiconductor is to be n-type and doped with 1 x 1015 cm3 donor atoms. Assume complete ionization and that Na=0. The effective density of state functions are given by Nc = Nv =1.5 x 1019 cm3 and are independent of temperature. A particular semiconductor device fabricated with this material requires the electron concentration to be no greater than 1.01 x 1015 cm 3 at T=400K. What is the minimum value of the band gap energy