Study and answer

Consider an n-type semiconductor with ND = 10 em . There is a uniform applied electric field, E = 10 V / em, throughout the semiconductor. At t = 0, the semiconductor was illuminated by a sharply focused pulse of laser to create an excess hole concentration of Ap(t = 0) = 102cm at x = 0. Find the expression for the excess hole concentration, Ap(a, t), as a function of x and t fort > 0, i.e. after the laser pulse is gone. Write your expression in terms of applied electric field, E, generation rate G, minority carrier lifetime, T, diffusion coefficient, D and mobility, A. Subscript p can be omitted for simplicity.Based on the history of marsupial colonization, extinction, and vicariant events, which of the following should be true of currently existing marsupials Select one: a. A phylogenetic tree should demonstrate that North American marsupials are most closely related to Australian marsupials O b. South American marsupials should be most closely related to Australian marsupials O c. South American marsupials should be most closely related to North American marsupials O d. None of the above