Physics of Semiconductor Devices

Conduction band electron energy

In silicon, the bottom of the conduction valley along the (100) direction is at (2π/a)(0.85,0,0) where a = 0.543 nm. Electrons in this valley have an anisotropic effective mass. The effective mass in the (100) direction is m_l^* = 0.98m₀ and the effective mass transverse to the [100] direction is m_t^* = 0.19m₀. What is the energy of an electron with a k-vector (2π/a)(0.9,0.07,0.04)?