EE40 Homework #6 Due Friday, May 27th 1:00pm, in the mail box of TA: Wendian Shi, In Moore Building Office Hours: Luke Guo ([email protected]): Monday 4:00pm – 6:00pm, Moore 239 Alexander Hu ([email protected]): Monday 9:45pm – 11:45pm, Moore 139 Hyung Wan ([email protected]): Tuesday 9:00pm – 11:00pm, Moore 139 Important: all problems to be solved for room-temperature (300K), and under equilibrium. Tables of fundamental constants and properties of select semiconductors are available on the class website and should be used when required values are not explicitly stated in the question. Question 1. Charged-Couple Device (40%)Question 2. MOSFET (40%) In previous models, we have assumed that the potential of the bulk is tied to that of the source, nullifying the JFET on the back side of the MOSFET. In this question, we will analyze the effects of having a variable potential on the substrate. We will also examine the affects of the Early voltage. ND = 1016 cm-3 NA = 5*1016 cm-3 ni = 1010 cm-3 tox = d = 1000 Å εs = 11.7 ε0 εox = 3.7 ε0 W = 100 µm L = 20 µm µn*Cox = 50 µA/V2 a. Calculate the current through the transistor with Vgs = 3.5V, Vds = 5V, Vsb = 0V and Vgs = 3.5V, Vds = 2.0V, Vsb = 0V (Assume VFB = 0V). (10%) b. The MOSFET threshold voltage VT is defined as the gate-source voltage required to drive the device into strong inversion. Derive an expression for the threshold voltage VT in terms of ΨB, VSB, VFB, and other device parameters and constants. (Hint: the expression should be of similar form to the original VT equation). Please explain the reasoning behind each step of your derivation. (6%) c. Please describe what affect this will have on the ability to drive current through a MOSFET. (6%)d. Recalculate the current found in part a) with Vsb of 0.5V. (6%) e. MOSFETs also experience an Early voltage similar to BJTs defined as Derive the expression for Early Voltage in a MOSFET as a function of L’. (6%) f. Please explain how this affects the current flow and redraw the I-V curves. (6%) Question 3 - Seebeck Effect (20%) i. Let lead a be Chrome and lead b be Copper and assume T=300K and ∆T = 5 K. Calculate ∆V . Use the Seebeck coefficients found in the class notes (be careful with the polarity). (10%) ii. Seebeck Coefficients in Si (10%) Given 19 32.88 10 cmcN−= × and 19 31.08 10 cmvN−= × in Si, calculate the Seebeck coefficients at 300K for two Si samples, one with 15 35 10 cmaN−= ×and the other with 15 35 10 cmdN−=