Browsing by Author "LIEN, CH"

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ENHANCEMENT OF THE STARK-EFFECT IN ALINAS/GAINAS COUPLED QUANTUM-WELLS AND THEIR APPLICATIONS TO TUNABLE MIDINFRARED PHOTODETECTORS
(1994-09-01)
HUANG, YM
;
LIEN, CH
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A tunable midinfrared photodetector using 1 --> 4 intersubband Stark shift in the four-level AlInAs/GaInAs coupled quantum wells (CQWs) is proposed. The operation of this device is based on the infrared absorption by the electrons in the ground state transited from the ground-state subband E1 of the CQWs to the third-excited-state subband E4. A large variation of eigenenergy spacing DELTAE41 between E1 and E4 under an applied electric field can be achieved for the proposed AlInAs/GaInAs CQW system. Since the infrared radiation is absorbed via the intersubband resonance absorption (homegaBAR = E4-E1), the detected infrared wavelength can be tuned by the spacing DELTAE41 which can be adjusted by an applied electric field. The tunability of these AlInAs/GaInAs CQWs have been studied theoretically. Based on theoretical calculations, tuning ranges from 3 to 3.9 and 2.9 to 4.2 mum are predicted for the proposed asymmetric CQW structure and compositionally asymmetric COW structure, respectively. This tuning capability is achieved by varying the applied electric field in the 90 to -90 kV/cm range.
ENHANCEMENT OF THE STARK-EFFECT IN ALINAS/GAINAS COUPLED QUANTUM-WELLS AND THEIR APPLICATIONS TO TUNABLE MIDINFRARED PHOTODETECTORS
(1994-09-01)
HUANG, YM
;
LIEN, CH
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A tunable midinfrared photodetector using 1 --> 4 intersubband Stark shift in the four-level AlInAs/GaInAs coupled quantum wells (CQWs) is proposed. The operation of this device is based on the infrared absorption by the electrons in the ground state transited from the ground-state subband E1 of the CQWs to the third-excited-state subband E4. A large variation of eigenenergy spacing DELTAE41 between E1 and E4 under an applied electric field can be achieved for the proposed AlInAs/GaInAs CQW system. Since the infrared radiation is absorbed via the intersubband resonance absorption (homegaBAR = E4-E1), the detected infrared wavelength can be tuned by the spacing DELTAE41 which can be adjusted by an applied electric field. The tunability of these AlInAs/GaInAs CQWs have been studied theoretically. Based on theoretical calculations, tuning ranges from 3 to 3.9 and 2.9 to 4.2 mum are predicted for the proposed asymmetric CQW structure and compositionally asymmetric COW structure, respectively. This tuning capability is achieved by varying the applied electric field in the 90 to -90 kV/cm range.
THE ENHANCED STARK EFFECTS OF COUPLED QUANTUM-WELLS AND THEIR APPLICATION TO TUNABLE IR PHOTODETECTORS
(1993-08-15)
HUANG, YM
;
LIEN, CH
;
LEI, TF
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A tunable asymmetric coupled quantum well far-infrared photodetector is proposed in this paper. The basic asymmetric coupled quantum wells are composed of two quantum wells separated by a thin barrier. In this way, the electron in each well interacts strongly with other electrons to achieve a large Stark tuning effect. The eigenenergies and the wave functions of the quantum-well structures are solved by the self-consistent method, and the effect of the exchange interaction on the ground-state subband has also been taken into account. The absorption coefficient is evaluated by the density-of-states formalism. Based on theoretical calculations, tuning ranges from 8.2 to 11.3 mum and 7.8 to 10.5 mum are predicted for the proposed asymmetric coupled-quantum-well structure and high-low coupled-quantum-well structure, respectively. This tuning capability is achieved by varying the applied electric field in the 20-90-kV/cm range.