Ultra wide band CW THz wave generation with ultra narrow line width

本文首次采用原始液相法在低温和恒温条件下生长了层状半导体晶体GaSe。由于生长温度低，可以实现纯的单ε相晶体。结果表明，化学计量控制改善了红外和太赫兹吸收特性。电学评价结果表明，与市售的Bridgman生长晶体相比，我们的液相生长晶体含有较少的原生点缺陷。为了降低自由载流子的吸收，通过掺杂过渡元素杂质，可以在带隙中引入深能级。利用液相生长的晶体，实现了太赫兹的产生，输出功率高达3mW左右。结果表明，与市售的Bridgman生长晶体相比，该晶体的产生效率提高了一个数量级。

Layered semiconductor crystal GaSe was grown for the first time by using our original liquid phase method at low and constant growth temperature. Due to the low growth temperature, pure single epsilon phase crystals can be realized. It is shown that the stoichiometry control improved the IR and THz absorption characteristics. From the electrical evaluation results, it is noticed that the our liquid phase grown crystals contain less native point defects compared with those in commercially available Bridgman grown crystals. In order to reduce the free carrier absorption, transition element impurity was doped and then deep levels can be introduced in the band gap, as expected. By using our liquid phase grown crystals, THz generation was realized with the output power up to about 3mW. It is shown that the generation efficiency was improved by one order of magnitude compared with that of commercially available Bridgman grown crystals.