Germanium-on-Glass solar cells: fabrication and characterization

We report on Germanium on Glass solar cells realized by wafer bonding, layer splitting and epitaxial regrowth. We provide a detailed description of the layer transfer process and discuss the material characterization. The solar cells are fabricated and tested to extract the most significant figures of merit, evaluating their performance versus device area and operating temperature. The cells exhibit typical conversion efficiencies exceeding 2.4% under AM1.5 irradiation and a maximum efficiency of 3.7% under concentrated excitation. This Germanium on Glass approach is promising in terms of added flexibility in multi-junction engineering and allows a significant cost reduction thanks to the re-usability of the Ge substrates

Steps towards the hyperfine splitting measurement of the muonic hydrogen ground state: pulsed muon beam and detection system characterization

The high precision measurement of the hyperfine splitting of the muonic-hydrogen atom ground state with pulsed and intense muon beam requires careful technological choices both in the construction of a gas target and of the detectors. In June 2014, the pressurized gas target of the FAMU experiment was exposed to the low energy pulsed muon beam at the RIKEN RAL muon facility. The objectives of the test were the characterization of the target, the hodoscope and the X-ray detectors. The apparatus consisted of a beam hodoscope and X-rays detectors made with high purity Germanium and Lanthanum Bromide crystals. In this paper the experimental setup is described and the results of the detector characterization are presented

Wavelength sensitive device for wavelength stabilization

A device for stabilizing the operating wavelength () of an electro-optical component having a nominal operating wavelength (0) by a wavelength influencing circuit adapted to be driven by a control signal. The device comprises a semiconductor photodiode adapted to be impinged upon by the radiation generated and/or processed by the component and to generate an output signal which is indicative of a difference of the wavelength of the radiation (() with respect to the nominal operating wavelength (0, i). The semiconductor photodiode includes a plurality of layers jointly defining two opposite diodes generating opposite photocurrents as a result of radiation impinging onto the photodiode. The opposite photocurrents are adapted to generate the control signal to effect the stabilization action