Based on the analytical solution to quantum confinement states inone-dimensional crystals with asymmetric potentials, it is shown thatthe confined states within the energy bands of asymmetric quantum well(AQW) have potentials to be sources of THz radiation. The calculationdemonstrates that it is the band mixture effect of AQW that makes theenergy separation variable to favour THz emission. Compared with singlethe quantum well with symmetric potentials, the electronic structure of AQWmakes it a desirable source of THz emission.