Hergo-H Wehmann

Performance of InGaAs metal-semiconductor-metal photodetectors on Si

The performance of In/sub 0.53/Ga/sub 0.47/As metal-semiconductor-metal photodetectors on Si substrates was investigated. The devices were fabricated by standard technology employing metalorganic vapor-phase epitaxy growth on unpatterned exactly [001]-oriented Si substrates and conventional photolithography. At a bias voltage of 5 V the devices exhibit low dark currents of 10/sup -6/-10/sup -7/ A, a high responsivity of 0.26 A/W at 1.3 /spl mu/m, and a cutoff frequency of 1.5 GHz. A further improvement could be achieved by increasing the bias voltage.

Improved thermal stability of In/sub 0.53/Ga/sub 0.47/As metal-semiconductor-metal photodetectors with Al/sub 2/O/sub 3/ interfacial layer

The thermal stability of In/sub 0.53/Ga/sub 0.47/As metal-semiconductor-metal photodetectors has been improved by using thin electron-beam evaporated Al/sub 2/O/sub 3/ interfacial layers of different thickness. The addition of the interfacial layer allows for an increase in anneal temperature from 250/spl deg/ to 350/spl deg/C with a four-fold dark current increase. Measurements of impulse responses at 1.3 /spl mu/m showed, that the frequency behaviour is not adversely affected by the increased capacitance caused by oxide charges, since metal-semiconductor-metal photodetectors are carrier transit-time limited.<<ETX>>

Area-selective diffusion of Zn in InP/In0.53Ga0.47As/InP for lateral pn photodiodes

Zn-diffusion experiments were performed in an open furnace with InP and In 0.53 Ga 0.47 As using Zn 3 P 2 , and Zn 3 As 2 as source materials, respectively. A reproducible diffusion, as expected from the literature, was observed with InP in the temperature range between 400 and 600 o C and with In 0.53 Ga 0.57 As at 550 o C. Area-selective diffusion was performed through evaporated Al 2 O 3 masks. Anomalously enhanced lateral diffusion under the mask observed with In 0.53 Ga 0.47 As was suppressed by a 200 nm thick InP cap layer between the ternary layer and the mask. A dark current density of as low as 40 pA/μm 2 at a reverse bias of 5 V, measured with lateral diodes, shows that a nonleaky lateral pn junction was formed, which is effective in separation of optically generated free carriers. The response time at 15 V reverse bias was 35 ps for a photodetector with an electrode separation of 6 μm. Simultaneously, low RC charging times in a 50 Ω load of 10 ps were found for the same bias conditions indicating that the transient behavior of the lateral pn photodiode is dominated by electron drift

Properties of InGaAs-MSM-photodetectors on Si

In this contribution the fabrication of lattice-mismatched InGaAs metalsemiconductor-metal (MSM) photodetectors on [001]Si substrates by metal-organic vapour-phase epitaxy (MOVPE) is described. Their characteristics are compared to lattice-matched devices on InP as well as to literature data. We found that the main differences of the detector performances on Si and InP are not related with the above mentioned defects but with an increased background doping concentration associated with the incorporation of Si into the growing layers.