Severe Fermi level pinning at the interface between n-Ge and a metal, leads to the formation of a Schottky barrier, almost independent on the metal work function. Therefore it seems impossible to form metal Ohmic contacts on moderately, n-type doped Ge layers. For p-type Ge the Fermi level pinning works opposite: all metal contacts show Ohmic behavior. This fixed behavior can be altered by the introduction of a thin Ge 3 N 4 layer. Ge 3 N 4 seems effective in reducing Fermi level pinning and therefore allows the formation of Ohmic contacts on n-type Ge and a rectifying contact on p-type Ge.

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The transmission properties of semiconductor surfaces can be changed by surface texturing. We investigate these changes experimentally and find that an enhancement of the angle-averaged transmission by a factor of 2 can be achieved with optimum texturing parameters. This enhanced transmission provides an additional light extraction mechanism for high-efficiency surface-textured light-emitting diodes. External quantum efficiencies of 46% and 54% are demonstrated before and after encapsulation, respectively.

We present an analytical model that allows to calculate the current response of a spatially modulated light CMOS detector (SML-detector) and compare this response with the response of a traditional CMOS photodetector. It is shown that the SML detector already yields a three orders of magnitude faster response time than a traditional CMOS detector in a 0.25 m CMOS technology. This response time will further decrease as CMOS technology evolves. This analytical expression is compared with a numerical solution of the diffusion equation and with experimental results. Both show an excellent correspondence. Therefore we can conclude that the SML-detector is the solution of choice for cheap, CMOS-compatible receivers in integrated opto-electronic systems.Index Terms-CMOS analog integrated circuits, optical receivers, photodetectors.