InAlGaAs/InP Light Emitting Transistors and Transistor Lasers Operating Near 1.55 microm

Light emitting transistors (LETs) and transistor lasers (TLs) are newly-emerging optoelectronic devices capable of emitting spontaneous or stimulated light while performing transistor actions. In the form of a heterojunction bipolar transistor (HBT) with quantum wells (QWs) incorporated in the base region, LETs and TLs opens up many immediate and potential applications in optoelectronic integrated circuits and high-speed photonics. This dissertation describes the design, growth, and performances of long wavelength LETs and TLs based on InAlGaAs/InP material system.;First, the doping behaviors of zinc (Zn) and carbon (C) in InAlGaAs bulk layers for p-type doping were investigated and clarified. Zn is found to be very diffusive in semiconductor matrix and can by contained in the base region only when the doping is lower than 4x1018 cm-3 and growth engineering is employed. On the other hand, C doping shows a low diffusivity and high doping levels but the material quality of C-doped InAlGaAs layers is poor. Using both dopants, the N-InP/p-In0.52(Al xGa1-x)0.48As/N-In0.52Al 0.48As LETs with InGaAs QWs demonstrate both light emission and current gain (beta). The Zn-doped LET shows a beta of 45, making it more like an HBT while the C-doped LET shows stronger light output at 1.65 microm, making it more like a light emitting diode (LED). A charge control analysis was proposed to explain the different device performances in Zn- and C-doped LETs.;A TL based on a C-doped double heterostructure (DH-TL) was designed and fabricated. The device lases at liquid nitrogen temperature with a threshold current density (Jth) of 2.25 kA/cm2, emission wavelength (lambda) at ∼1.55 microm, and beta of 0.02. The strong intervalence band absorption (IVBA) is considered as the main intrinsic optical loss that limits the optical output and prohibits the device from lasing at room temperature. The threshold condition in long wavelength InAlGaAs/InP TLs was then theoretically and numerically investigated. It is found that room-temperature lasing of a DH-TL is achieved only when the base thickness and doping level are within a specific narrow range. However, the selectable range is significantly expanded by mean of facet coating, structure engineering, and QW design. By using a more compressively-strained or thicker QW as the active region in a separate confinement heterostructure TL (SCH-TL), it is possible to obtain a Jth as low as sub-100 A/cm2.