A novel 3D stacking method for Opto-electronic dies on CMOS ICs.

A high speed, high density and potentially low cost solution for realizing a compact transceiver module is presented in this paper. It is based on directly bonding an Opto-electronic die on top of CMOS IC chip and creating a photoresist ramp to bridge the big step (around 220 µm) from Opto-electronic pads to CMOS IC pads. The required electrical connection between them is realized lithographically with a process than can be scaled to full wafer production. A 12-channel transmitter based on the technique was fabricated and test shows good performance up to 12.5 Gb/s/ch.

Real versus measured surface potentials in scanning Kelvin probe microscopy.

Noncontact potentiometry or scanning Kelvin probe microscopy (SKPM) is a widely used technique to study charge injection and transport in (in)organic devices by measuring a laterally resolved local potential. This technique suffers from the significant drawback that experimentally obtained curves do not generally reflect the true potential profile in the device due to nonlocal coupling between the probing tip and the device. In this work, we quantitatively explain the experimental SKPM response and by doing so directly link theoretical device models to real observables. In particular, the model quantitatively explains the effects of the tip-sample distance and the dependence on the orientation of the probing tip with respect to the device.