37 GHz direct modulation bandwidth in short-cavity InGaAs/GaAs MQW lasers with C-doped active regions

We have recently reported short-cavity In_0.35Ga_0.65As/GaAs MQW lasers with modulation bandwidths up to 33 GHz using beryllium (Be) as p-dopant in the active region. At the growth temperatures used for this structure, however, a modulation-type p-doping in the core can not be realized due to the redistribution of Be during the growth process. In this work, we present InGaAs/GaAs MQW lasers with a similar epilayer structure, but with the Be-doping in the core replaced by carbon (C), resulting in a modulation-doped core region. Short-cavity lasers fabricated using this epilayer structure demonstrate record CW direct modulation bandwidths up to 37 GHz in 6x130 μm² devices at room temperature