The effect of arsenic on MBE-grown modulation-doped GaAs/AlGaAs heterostructures

In this paper, the effect of As on the mobility and junction electric field of modulation-doped GaAs/AlGaAs heterostructures were investigated by varying the As flux during the MBE growth of the samples. Hall measurements using the van der Pauw configuration determined the carrier concentration and Hall mobility. The carrier concentration was observed to increase with As flux. The room temperature mobilities of the samples tend to decrease, while the 77 K mobilities increase with increasing As flux. Photoreflectance spectroscopy was utilized to derive the junction electric field. These values were observed to be higher than the electric field values calculated from Hall measurements for the samples grown at relatively lower As fluxes. This may be the effect of electron traps due to As vacancies coupled to C impurities. A remarkable improvement in the 77 K mobility of the sample grown after baking the substrate holder was observed. The 10 K mobility however was low compared to the benchmark set by other groups

Investigation of Advanced Dicing Technologies for Ultra Low-k and 3D Integration

© 2016 IEEE. The introduction and use of ultra low-k dielectric materials in an attempt to achieve better die performance brought new challenges to the wafer singulation / dicing process. Ultra low-k dielectric materials can easily get damaged during conventional blade dicing due to their brittleness. Thus, there is a need to investigate alternative or more advanced dicing techniques that can deliver successful dicing processes without inducing stress or damage. Apart from looking at the compatibility of the different dicing techniques with (ultra) low-k dielectric materials, the integration of these different dicing techniques into the different 3D-Technology configurations was also investigated. This paper reports on the post dicing results and the challenges for 3D technology for the following different dicing technologies: blade dicing, laser grooving + blade dicing, laser grooving + plasma dicing, stealth dicing, plasma dicing, and laser full cut dicing.status: publishe