The authors report on picosecond pulse response GaNAsSb∕GaAs p-i-n photodetectors grown by molecular beam epitaxy in conjunction with a rf plasma-assisted nitrogen source. The 2μm thick GaNAsSb photoabsorption layer contains 3.3% of N and 8% of Sb resulting in a dc photoresponse up to 1380nm wavelength. Dark current densities at 0 and −5V are 1.6×10−5 and 13A∕cm2, respectively. The GaNAsSb photodiodes exhibit a record pulse response width of only 40.5ps (full width at half maximum) corresponding to a 4.5GHz bandwidth.

Experimental demonstration of pseudomorphic heterojunction bipolar transistors with cutoff frequencies above 600 GHz Appl. Phys. Lett. 86, 152101 (2005); 10.1063/1.1897831Comparison of As-and P-based metamorphic buffers for high performance InP heterojunction bipolar transistor and high electron mobility transistor applications High gain AlGaAs/ GaAs heterojunction bipolar transistors grown on SiGe/ Si substrate have been fabricated. Measured peak dc current gain of ϳ100 is obtained for a device with emitter area of ϳ1.6ϫ 10 3 m 2 , with base concentration of 1 ϫ 10 19 cm −3 . The dominant base current component is discussed and determined. The breakdown characteristic is studied and compared with that of the device grown on GaAs substrate. Our experimental results demonstrate that SiGe/ Si substrate could provide a robust method for monolithic integration of high speed GaAs-based electronic devices with silicon-based circuitry.

Articles you may be interested inDeep-level traps induced dark currents in extended wavelength InxGa1−xAs/InP photodetector We present the reverse-bias current-voltage and deep-level transient spectroscopy ͑DLTS͒ characteristics of a Ga 0.90 In 0.10 N 0.033 As 0.967 / GaAs positive-intrinsic-negative photodiode ͑E g = 0.92 eV͒ and a trap-assisted tunneling model which considers generation-recombination and tunneling mechanisms. Using trap parameters obtained from the DLTS measurement, the model generates current-voltage characteristics of the photodiode, which were found to be in good agreement with experimental current-voltage curves at different temperature. The model also suggests that high dark current at low reverse-bias voltage is caused by the presence of traps which have low activation energy. Furthermore, it is predicted that approximately ten times reduction in the dark current can be achieved when the trap concentration of type H-1 ͑E a = 0.15 eV͒ is reduced by one order. On the other hand, a similar reduction in defect concentration of type H-2 ͑E a = 0.40 eV͒, which is nearer to midgap does not produce the same effect.

A GaAsSbN layer closely lattice matched to GaAs was used as an intrinsic layer ͑i layer͒ in a GaAs/ GaAsSbN / GaAs p-i-n photodiode with response up to 1.3 m. Deep level transient spectroscopy measurement on the GaAs/ GaAsSbN / GaAs reveals two types of hole traps ͑HTs͒ in the GaAsSbN i layer; ͑i͒ HT 1 : a shallow N-related defect state ͑E a ϳ 0.10-0.12 eV͒ and ͑ii͒ HT 2 : an As Ga point defect-related midgap defect state with E a ϳ 0.42-0.43 eV. Reduction in growth temperature from 480 to 420 °C reduces the HT 2 trap concentration from 4 ϫ 10 15 to 1 ϫ 10 15 cm −3 , while increases the HT 1 trap concentration from 1 ϫ 10 14 to 7 ϫ 10 14 cm −3 . Reduction in the HT 2 trap concentration following growth temperature reduction was attributed to the suppression of As Ga point defect formation. Evidence of possible change of the As Ga midgap state to a shallow level defect due to the formation of ͑As Ga -N As ͒ pairs was also suggested to have increased the HT 1 trap concentration and reduced the HT 2 trap concentration. An ϳ4 dBm improvement in photoresponse under 1.3 m laser excitation and approximately eight times reduction in dark current at −8 V reverse bias were attributed to the reduction in the overall trap concentration and mainly the reduction of the As Ga -related midgap trap concentration in the sample grown at 420 °C.

We studied the electroluminescence and structural characteristics of five-layer stacked self-assembled InAs/In0.1Ga0.9As quantum dot (QD) structures grown on graded Si1−xGex/Si substrate. The QD was found to take on a lens shaped structure with aspect ratio of 0.23±0.05. Room-temperature electroluminescence at 1.29 μm was observed from the QD structures. The external quantum efficiency as function of injected current was investigated and the dominant carrier recombination processes were identified from analysis of the current-optical power relationship.