In this paper, an account is presented of the semiconductor, because of the energy gap bipolar with electron (e) and hole (h) conductivity, becoming ingeniously with little or no technology (Bardeen and Brattain, Dec. 1947) the transistor, a triode (at first just a germanium “base” crystal and a point contact “emitter” and “collector”), a low impedance “emitter” minority carrier input (IE) into a (the) vital central “base” active region, the base supporting along with essential recombination current IB(IB> 0) carrier transport to a higher impedance “collector” output IC( IE+IB+IC=0, IC/IE=α ~ 0.9), hence gain, thus revealing at last that a current (IB) can increase the electron-hole (e-h) population, and as a further consequence, yield band-to-band (ke=kh) excess carrier recombination radiation (light). The transistor established (1947) a basis for the study of the light-emitting diode (LED). The path to an “ultimate lamp,” the p-n diode laser and LED, is described from semiconductor, to energy gap, e-h bipolarity, transistor, the p-n transition, excess carriers, e-h recombination, direct gap (ke=kh) crystal, autocatalytic e-h/photon interaction, spectral narrowing, stimulated recombination (laser), need for resonator (cavity Q, how?), direct-gap (ke=kh) III-V alloy, visible spectrum III-V alloy, III-V alloy gap change (ΔEg), quantum-well (QW) e-h recombination, stimulated emission solving the problem of photon extraction ( → 100% quantum efficiency), the p-n diode “ultimate lamp,” return to the 1947 triode, to the transistor, and the base importance informing the realization of a QW-base transistor laser.

The quantum-well (QW) heterojunction bipolar transistor (HBT) laser [the transistor laser (TL)], inherently a fast switching device, operates by transporting small minority base charge densities$\sim\!\! {\hbox {10}}^{16}\ {\hbox {cm}}^{-3}$over nanoscale base thickness ($<$900 A) in picoseconds. The base QW acts as an optical “collector,” in addition to the usual electrical collector, that selects out “fast” recombining carriers, resulting in a short lifetime ($\sim$29 ps) and higher differential laser gains. Charge and current continuity, together with the boundary conditions imposed by both collectors of the TL lead to a new charge control model, “unpinning” of population inversion beyond lasing threshold, quasi-Fermi level discontinuity across base QW, and a new equivalent circuit model requiring an extension to Kirchhoff's law. With the TL, the HBT becomes more than just a charge control device, but also a photon storage and switching device. The TL, owing to fast recombination speed, its unique three-terminal configuration, and the complementary nature of its optical and electrical collector output signals, enables resonance-free base current and collector voltage modulations, and compact realization of electro–optical applications such as nonlinear signal mixing, frequency multiplication, negative feedback, and optoelectronic logic gates.

The long-range vision of the Engineering Research Center for Compound Semiconductor Microelectronics (CCSM) is focused on a new generation of high-speed communications and data-processing technology which exploits the bandwidth, immunity to electromagnetic interference, and connectivity of optical interconnects. In order to realize this vision, it will be necessary to design, fabricate, and integrate high-performance electrical and optical devices in monolithic optoelectronic integrated circuits, OEIC's. The research programs of the CCSM are focused on the development of the engineering science and technology base for fabrication of OEIC's and their application in optical interconnect systems; the education of engineers in this field; and effective transfer of this technology to industry