Laser operation of a heterojunction bipolar light-emitting transistor

Data are presented demonstrating the laser operation (quasicontinuous, $∼200K$⁠) of an InGaP–GaAs–InGaAs heterojunction bipolar light-emitting transistor with AlGaAs confining layers and an InGaAs recombination quantum well incorporated in the $p$-type base region. Besides the usual spectral narrowing and mode development occurring at laser threshold, the transistor current gain $β=ΔIc∕ΔIb$ in common emitter operation decreases sharply at laser threshold $(6.5→2.5,β>1)$⁠.