For pure GaAs at300 K, the concentration of electrons in the conduction band is equal to that of holes in the valence band (= 2 x 10⁶/cm³). Now we introduce selenium (Se) impurities at a concentration of 1 x 10¹⁶/cm³ into GaAs. Se is a group VI element sitting on As sites. Assume that all dopants are ionized and e = 1.6 x 10⁻¹⁹ C.
(a) What is the conductivity type (n or p)?
(b) Calculate the electron and hole concentrations.

Ajournal bearing has a journal diameter of 3.250 in with a unilateral tolerance of 20.003 in. the bushing bore has a diameter of 3.256 in and a unilateral tolerance of 0.004 in. the bushing is 2.8 in long and supports a 700-lbf load. the journal speed is 900 rev/min. find the minimum oil film thickness and the maximum film pressure for both sae 20 and sae 20w-30 lubricants, for the tightest assembly if the operating film temperature is 160°f. a computer code is appropriate for solving this problem.

Which one from below is not one of the reasons of planning failures? (clo3) a)-planner is careless. b-planner spend less time in the field but more time on the desk c)-planner is not qualified d)-planner does not have sufficient time to properly plan

An air compression refrigeration system is to have an air pressure of 100 psia in the brine tank and an allowable air temperature increase of 60°f for standard vapor compression cycle temperatures of 77 f entering the expansion cylinder and 14 f entering the compression cylinder, calculate the coefficient of performance a. 2.5 b 3.3 c. 4.0 d. 5.0