Design and analysis of GRIN-SCH-SQW transistor laser

Graded index separate confinement heterostructure (GRIN-SCH) has been suggested for n-InGaP/p
⁺
-GaAs+i-InGaAs/i-GaAs single quantum well (SQW) transistor laser (TL) with linearly graded In
_ξ
Ga
_1-ξ
As in base region (ξ : 0 → 0.029 emitter to QW and ξ : 0.038 → 0.05 from QW to collector). Charge control model is used to analyze the proposed device. The model has been modified to describe graded effects. Due to using graded base structure, base transit time reduces from 1.4 ps to 0.8 ps by the induced built-in potential, resulting in an increase of 3dB bandwidth in a device with an emitter size area of 4000 μm
²
and 150 μm cavity length.