| 摘要 |
An semiconductor structure comprises a first quantum well having a first bound state E3 with an energy that is greater than an energy of a lower state El by a first energy difference, a quantum well structure 100 adjacent to the first quantum well and having at least a second bound state E4 having an energy level which is resonant with the first bound state E3 of the first quantum well, a second quantum well having at least a third state E2 to collect electrons from the second bound state E4 of the quantum well structure through a non-radiative mechanism and a fourth bound state E5. An energy of the fourth bound state of the second quantum well is greater than an energy of the third state E2 by a second energy difference. The structure can absorb two photons, one in the first quantum well by excitation of a carrier from the lower energy state El to the first bound state E3 and another in the second quantum well by excitation of a carrier from the third state E2 to the fourth bound state E5. The quantum well structure provides efficient extraction of excited carriers from the first quantum well. |
