|Budget Amount *help
¥5,500,000 (Direct Cost : ¥5,500,000)
Fiscal Year 1991 : ¥1,100,000 (Direct Cost : ¥1,100,000)
Fiscal Year 1990 : ¥4,400,000 (Direct Cost : ¥4,400,000)
Stimulated, interband Landau emission originating from the excitation of electrons and holes by the action of the J X H force at the quantum limit has been discovered in bulk n-type InSb at 4.2 - 135 K, accompanied by a current saturation in the V - I curve, when passing a current density J, as low as 1640 A/cm^2 for H = 7 T at 80 K for example, in perpendicular to the applied magnetic field H.
At the quantum limit, the excited electrons and holes are almost populated in the lowest Landau levels yielding the inverted population at the current densities above the threshold value Jc. Then, the gain, g (omega, H), of the Landau emission at the band edge (k_z= 0) has been shown to be divergently high value for the (O_+ -> O') and (O_<_> -> O') transitions, explaining well such an extremely small value of Jc.
The polarization measurements have revealed that the extraordinary mode is the favorable one to suffer the selective amplifier in the sample.
The similar Landau emission has also been observed at room temperature in high magnetic fields above 6 T, from which the band parameters, such as epislon_g = 0.18 eV, m^* _1(0)= 0.015 m_o and g_1(O)= -47, have been determined for InSb at room temperature.
The similar phenomena have been verified for Hg_<0.8>Cd_<0.2>Te, but with the quantum efficiency of about 1/20 of InSb samples.