DC and AC characteristics of delta-doped GaAs FET

Molecular-beam-epitaxy-grown GaAs field-effect transistors (FETs) using a delta-doped channel are discussed. FETs having gate lengths of 1.3 μm showed transconductances as high as 290 mS/mm at a current density of 200 mA/mm. The measured f_T was 14.5 GHz and the extracted f_max was 30 GHz. These results are the best reported in a FET with this material structure having a delta-doped channel     

DC and RF performance of GaAs MESFET fabricated on silicon substrate using epitaxial lift-off technique

GaAs MESFETs have been fabricated on a silicon substrate using a molecular beam epitaxy grown film detached from its growth substrate and attached on a silicon substrate covered with a dielectric. The device processing is done on the silicon substrate. The MESFETs exhibit I/sub DSS/=130 mA/mm, g/sub m/=135 mS/mm and for 1.3 mu m gate length unity current gain cut-off frequency f/sub T/ of 12 GHz. Excellent device isolation with subpicoampere leakage currents is obtained.<>     

Monolithic multiple wavelength surface emitting laser arrays

A two-dimensional (2-D) surface emitting laser array emitting 140 unique, nonredundant, uniformly separated, single-mode wavelengths in the 980-nm regime is described. The wavelength separation between neighboring lasers is as small as 0.3 nm. A large total wavelength span of 43 nm was obtained without compromising the performance of the lasers. All 140 lasers have nearly the same threshold currents, voltages, and resistances. The techniques used are generic and can be readily extended to both longer and shorter wavelength lasers. The authors also report the first wavelength division multiplexing system experiment using part of this laser array. A BER (bit-error ratio) of 10 ^-9 at 155 Mb/s was obtained with simultaneous operation of four lasers at a wavelength separation of 1.5 nm. Negligible optical and electrical crosstalk was observed between the lasers     

Grafted GaAlAs rib waveguides on an InP substrate

Rib waveguides were fabricated on a 1.4 mu m thick GaAlAs epilayer granted on the surface of a semi-insulating InP substrate by epitaxial lift-off. Single-mode waveguides with propagation losses (<7 dB/cm) lower than heteroepitaxially grown counterparts have been achieved. TEM analysis on the GaAlAs/InP interface indicates surface scattering as one of the main loss mechanisms.<>     

Dynamic, polarization, and transverse mode characteristics ofvertical cavity surface emitting lasers

The dynamic, polarization, and transverse mode characteristics of strained InGaAs-GaAs quantum well vertical cavity surface emitting lasers (VCSELs) emitting at 0.98 μm are investigated. The dynamic behavior of VCSELs with high and low operating voltages and series resistances is compared. A large wavelength chirp in the lasing spectrum was observed for the lasers with high voltage/resistance, even under low-duty-cycle pulse operation. This is thought to be due to resistive heating close to the laser junction. It is observed that the transverse mode structure of VCSELs and their dependence on laser dimensions and drive current are highly analogous to those of edge emitting lasers, whereas the polarization characteristics of the two types of lasers are significantly different     

A 150-MOPS GaAs 8-bit slice processor

The architecture, circuit design, and test results for a GaAs 8-b slice processor IC are presented. The device is a high-speed cascadable element intended for use in MIL-STD-1750A computers, reduced-instruction-set computer (RISC) systems, signal processors, and numerous other applications where high speed and radiation hardness are required. The bus-oriented architecture features a 31-word×8-b two-port register file, a fast eight-function ALU, an 8-bit address port an 8-b bidirectional data port, and associated shifting, decoding, and multiplexing functions. Ancillary logic commonly mechanized in external hardware has been included on-chip. The 9400-transistor LSI device demonstrated peak performance above 150 million operations per second (MOPS) at 9.2 W; a lower power version executes 100 MOPS at 4.2 W