Digital communication using Ge metal-insulator-semiconductor light-emitting diodes and photodetectors

Abstract

Both Ge light-emitting diodes and photodetectors are demonstrated by using the same metal-insulator-semiconductor (MIS) tunneling structure. A Ge MIS tunneling diode biased at the accumulation region is used as a light-emitting device and a Ge MIS tunneling diode biased at the inversion region is used as a photodetector. The ultrathin gate oxide film used in the MIS tunneling diode was grown by liquid phase deposition at 50 °C to lower the thermal budget. A Ge light-emitting diode has a higher quantum efficiency than a similar Si device (at least one order of magnitude stronger) due to the higher radiative recombination coefficient. With the detection of the Ge MIS photodetector, the data communication in free space is reported and demonstrated for the first time.

Metal-Insulator-Semiconductor Photodetectors

“…Ge photocapacitive mode MIS infrared photodetectors were proposed in 1979 [ 54 ]. In order to demonstrate the tunneling-photocurrent mode Ge MIS photodetector, a thin SiO 2 layer was formed on the Ge substrate with the process of low-temperature liquid phase deposition (LPD) [ 55 ]. Note that the insulator layer was SiO 2 instead of GeO 2 since GeO 2 was unstable and had a worse quality.…”

“…In [ 55 ], Ge MIS structures were both used as photodetectors and light-emitting diodes (LEDs). The Ge MIS structure with an inversion bias acted as a photodetector, while it acted as an LED with an accumulation bias.…”

“…The same MIS structure was used with different biases for different applications. The Ge MIS structure with an inversion bias acted as a detector, while it acted as an LED with an accumulation bias [ 55 ].…”

“…A delay time of ∼19 ns was observed in (b). Reprinted from [ 55 ] with permission of the American Institute of Physics (Copyright 2008).…”

Improved Si0.5Ge0.5/Si interface quality achieved by the process of low energy hydrogen plasma cleaning and investigation of interface quality with positron annihilation spectroscopy

“…Due to stronger photon absorption, 1 higher light emission efficiency, 2 higher carrier mobility, 3 and possible integration with Si, the SiGe-based optical devices, including SiGe solar cell and SiGe light-emitting diodes, 4 and SiGe-based electrical devices 5 are of great interests for the scientific research recently. One of the key issues and bottlenecks for the practical applications on the SiGebased devices is the interface quality between epi-SiGe layer and Si substrate due to the lattice mismatch.…”