| Budget Amount *help |
¥28,990,000 (Direct Cost: ¥22,300,000、Indirect Cost: ¥6,690,000)
Fiscal Year 2016: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
Fiscal Year 2015: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
Fiscal Year 2014: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2013: ¥20,280,000 (Direct Cost: ¥15,600,000、Indirect Cost: ¥4,680,000)
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| Outline of Final Research Achievements |
We investigated the amplification effect on (i.e., the gain for) terahertz electromagnetic waves in semiconductor superlattices with an emphasis on its physical nature and controllability at high temperatures, which artificial crystals contained an alternate stack of nanometer-thick GaAs and AlAs layers. Electrons created by optical pulses under dc voltage in the stacking direction were found to exhibit temporal waveforms of terahertz emission with a voltage- controlled oscillation frequency and a unique initial phase throughout the temperature range of 80-298 K. The complex conductivity spectra obtained using the phase information have offered direct evidence for the existence of room-temperature terahertz gain in semiconductor superlattices that originates from a capacitive nature of the electron system (without the conventional concept of population inversion).
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