Theoretical analysis on optoelectronic performances of long wavelength transistor lasers: base width variation effects

We investigate the base width variation effects on various optical and electrical characteristics of double heterostructure long wavelength transistor laser (DH-LWTL). Considering the device structure, the base region geometry of a LWTL significantly affects its optoelectronic performance. We derive theoretical approximation of optical confinement factor (OCF), where we study the relationship between the base width and the OCF. In order to analyze optoelectronic performance of the LWTL, however, we have to consider the optical loss in base region with intervalence band absorption as the main factor in our calculation approach. We show that both the OCF and the optical loss have opposite trends with base width variation. Transient parameters including resonance peak and frequency are also inspected for their dependence on the base width as well as doping concentration. According to our simulations, we expect a minimum threshold current density of \(4.38\, \hbox {KA/cm}^{2}\) and a maximum cut-off frequency of 28.22 GHz for 38 nm and 305 nm base widths, respectively. A relatively fast process of “carrier extinction” is also anticipated for narrow enough bases.