Terahertz amplification in delta-doped germanium films with in-plane transport

Amplification of terahertz radiation on intersubband transitions has been analyzed by numerical Monte Carlo simulation for p-type delta-doped Ge films with in-plane transport configuration of applied electric and magnetic fields. A significant increase of the gain is found, compared to existing bulk p-Ge lasers, due to spatial separation of light and heavy hole streams, which reduces scattering of light holes on ionized impurities and heavy holes. The considered device has potential as a widely tunable (2-4 THz) laser with high duty cycle and operating temperatures up to 50 K