摘要:
本文报道了采用分子束外延技术制备的三色InAs/GaAs量子点红外探测器.器件采用nin型结构,吸收区结构是在InGaAs量子阱中生长含有AlGaAs插入层的InAs量子点,器件在77 K下的红外光电流谱有三个峰值：6.3,10.2和11μm.文中分析了它们的跃迁机制,并且分别进行了指认.因为有源区采用了不对称结构,所以器件在外加偏压正负方向不同时,光电流谱峰值的强度存在一些差异.不论在正偏压或者负偏压下,当偏压达到较高值,再进一步增大偏压时,都出现了对应于连续态的跃迁峰强度明显下降的现象,这是由量子点基态与阱外连续态的波函数交叠随着偏压进一步增大而迅速减小导致的.
Abstract:
We report on a three-color InAs/GaAs quantum dot infrared photodetector grown by molecular beam epitaxy. The InAs quantum dots with AlGaAs inserting layers are formed on an InGaAs quantum well layer as an absorber region. The detector is an nin-type device, and three photocurret peaks at 6.3, 10.2 and 11 μm are observed at 77 K, respectively. Each peak is designated and the physical mechanism is discussed. The dependences of the intensities of the three peaks on the applied bias voltage are different for the positive and the negative bias conditions due to the asymmetric structure of the absorber region. The peak arising from the transition between the quantum dot ground state and a continuum state becomes weaker when the bias voltage is larger than a certain value. The physical reason is attributed to the decrease of the wavefunction overlap between the two quantum states.
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