| 학회 | 한국재료학회 |
| 학술대회 | 2013년 가을 (11/06 ~ 11/08, 제주롯데호텔) |
| 권호 | 19권 2호 |
| 발표분야 | A. 전자/반도체 재료(Electronic and Semiconductor Materials) |
| 제목 | Two-color InAs quantum dot infrared photodetectors realized by selectively positioned potential confinement layer |
| 초록 | Intensive research is focused on the applications of strain-driven coherent island based InAs/GaAs quantum dots (QDs), such as lasers and infrared (IR) photodetectors. Understanding and manipulation of the electronic states of these QDs are central to exploiting their full potential. Tuning of the QD electronic structure can be achieved by varying QD size, QD capping layers, or thermal annealing. Most such approaches affect the QD electronic structure as a whole and do not allow tuning primarily subsets of QD states. We demonstrated the possibility to manipulate specific subsets of QD states using a lateral potential confinement layer (LPCL) positioned at different height of QDs. Such a selective manipulation of QD states is very useful for tuning detection bands of quantum dot infrared photodetectors (QDIPs). In this presentation, we report two-color QDIPs for middle- and long-wavelength IR realized by selectively positioned LPCL. QDIPs were grown by molecular beam epitaxy on (001) undoped GaAs under As pressure of 7.0x10-6 torr. InAs QDs were formed by 2.0 ML InAs deposition at the rate of 0.22 ML/sec at 500oC. The QDIPs (n-i(QD)-n) comprised a stack of 5 InAs QD layers with 200 ML spacers and silicon-doped top and bottom contact layers. As a reference, the InAs QDs were capped by 20 ML In0.15Ga0.85As and 180 ML GaAs layers. To investigate the change in the electron intraband transitins of the QDIPs by a LPCL positioned at the bottom region of the QDs, the 7 MLs of the 20 ML In0.15Ga0.85As were replaced by In0.15Al0.25Ga0.60As. The PL and PLE studies show that the electron and hole ground states and the first subset of excited hole states are perturbed most effectively by the LPCL located in the bottom region of QDs, indicating that the charge center of gravity of these states resides near the QD bottom. Moreover, this results in two-color QDIP detection for middle- (~5 μm) and long-wavelength IR (~10 μm). We will discuss the complementary two-color QDIP information obtained from photoluminescence (PL), PL excitation and PC spectroscopies. |
| 저자 | Nguyen Tien Dai1, 박남규2, 김의태3 |
| 소속 | 1Department of Materials Science and Engineering, 2Chungnam National Univ., 3Daejeon |
| 키워드 | InAs; quantum dot; QDs; QDIPs; GaAs |
