103年 - 103 國立中山大學_碩士班招生考試_電機系(甲組)：半導體概論#110035

1. The electron and the hole concentrations in a silicon sample are shown below. The cross-sectional area of the sample is 2x10⁴ μm². Determine the total diffusion current versus distance x for 0≤x≤0.005cm.
  (10%)

4. Answer the following questions about MOS capacitor. (a) Explain the flat-band voltage. (5%)( b) Consider a n⁺polysilicon-SiO₂-Si capacitor with a p-type silicon substrate doped to N_A = cm, a silicon dioxide insulator with a thickness of 300 . The metal-semiconductor work function diference is -0.98 V. The fixed charge within the SiO₂-Si interface Q/q = 4✖The dielectric constant of SiO₂ is 3.9. Calculate the flat-band voltage. (15%)

5. For DRAM operation, assume that we need a minimum of 10⁵ electrons for the MOS storage capacitor. The capacitor has an area of 0.6 μmx 0.6 um on the wafer, an oxide thickness of 7 nm, and is fully charged to 3 V. What is the required minimum depth of a rectangular-trench capacitor?