Improvement of multiquantum-barrier effect by layer-thickness modulation

We propose a novel modulated-layer-thickness multiquantum-barrier (MQB) structure, or chirped MQB. The chirped MQB has a larger potential increase (240 meV) against overflowing electrons than the uniform MQB by almost 100 meV. It also has a broader optimum well thickness width of 1.9 nm while the uniform MQB has only 0.5 nm optimum width. This indicates that the chirped MQB would work more effectively even under the layer thickness fluctuation caused by step bunching, etc.