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Germanium is listed as a critical raw material, and for environmental and economic sustainability reasons, strategies for lower consumption must be implemented. A promising approach is Ge lift‐off concepts, which enable to re‐use the substrate multiple times. Our concept is based on the Ge‐on‐Nothing approach that is the controlled restructuring at high temperature of a macroporous Ge surface, forming a Ge foil weakly attached to its parent wafer. Its suitability as III–V epitaxy seed and support substrate has previously been demonstrated with proof‐of‐concept solar cells. This work focuses on bringing this concept to the next level, by upscaling the detachable area to a full 200‐mm wafer scale, increasing foil thickness for sufficient light absorption in the Ge bottom cell, and improving the control on the strength that is bonding the suspended foil to its parent. By introducing a new high growth‐rate epitaxy process from GeCl4, and by engineering the GeON structure to introduce pillars with ad hoc density and shape, we fabricated P‐type foils with tunable boron doping up to 15 μm in thickness and 11 cm × 11 cm in area, for which the detachment strength could be adapted to the stresses induced by the solar cell process steps. The surface roughness and the electrical and crystal qualities of these foils were inspected by AFM, SIMS, SRP, ECCI, and TEM to check the GeCl4‐based epitaxy conditions and to check that the ad hoc pillars were not introducing any damage. Small‐area triple‐junction lattice‐matched GaInP/GaInAs/Ge solar cells were fabricated on 7‐μm‐thick Ge foils with various pillar densities and on a standard reference Ge wafer. The III–V layer nucleation was virtually the same on both substrates and the solar cells on the GeON foils performed in the same way as the cells on the Ge wafer, albeit a small loss in short‐circuit current and open‐circuit voltage that can be attributed to the thickness reduction and absence of rear‐side passivation. We conclude that it is possible to gain control on the GeON detachability and upscale the concept to areas relevant for the space PV industry, proving that porous germanium is a serious candidate for replacement of bulk Ge wafers in view of a more sustainable multijunction solar cell process. [ABSTRACT FROM AUTHOR]

8′ Ge wafers were developed as the starting substrate for lattice‐matched hetero‐epitaxially grown As‐free AlGaInP layers for 650nm RED μ‐LEDs. This paper focusses on the challenges that we have encountered and the innovations that were needed to develop 8′ Germanium wafers for Arsenic free AlGaInP red μ‐LEDs. The results of germanium 8′ 0EPD crystals and low LPD/COP wafers from our pilot 8′ wafer line, will be shown. This paper also includes a comparison with Si and GaAs. [ABSTRACT FROM AUTHOR]

Umicore has been the leading Germanium substrate manufacturer over the last 20 years. We are only able to maintain that position by constantly improving the quality of our product. In this work, Umicore wants to present how it will continue this tradition by adding even more value to its product. In the beginning of 2014 we proposed to our customers to help them in achieving their yield improvement goals. Two main concerns were expressed: the breakage rate in their production line and non-uniform epi-growth. After two years of development, Umicore has bundled these two improvements into a new product. The ExpoGerTM wafer combines a better mechanical yield with a uniform, epi-ready surface enabling a narrower distribution of the electrical performance. The breakage rate of the customers is related to the wafers that suffer from early failure. The percentage of early failures is related to its thickness. With the trend towards even thinner substrates, it is important to add features that reduce the percentage of early failures. Two features are crucial: the shape of the substrate edge and the stress relief etch, which influences the wafer strength. Just as for the strength, two distinctive aspects define the surface quality. On the one hand, there are the number and size of surface defects, which have an important influence on the metal-organic chemical vapour deposition (MOCVD) growth performed at Umicore’s customers. On the other hand, drying marks, which are invisible to the naked eye, may lead to a local, non-uniform growth and they can be a precursor to time dependent haze issues. Umicore is able to demonstrate the impact of the ExpoGerTM processes on the strength and surface quality of its wafers and thus on the production yield of its customers.

We describe the DRAM-like approach towards a non-volatile magnetoresistive memory integrating magnetic and semiconductor devices into one cell. The speed at which the magnetic memory signal can be read depends on many factors. An important factor is the magnetic element itself, the size, magnetic characteristics and absolute resistance. Secondly, the design of the read-out electronics is a key issue. A third determining factor is the technology in which the electronics are fabricated. Some features are indicated that are essential in optimizing MRAM in future. Index Terms--Magnetic Random Access Memories, Spin-Valve, Tunnel-junction.