Bridging the gap between surface physics and photonics.

Use and performance criteria of photonic devices increase in various application areas such as information and communication, lighting, and photovoltaics. In many current and future photonic devices, surfaces of a semiconductor crystal are a weak part causing significant photo-electric losses and malfunctions in applications. These surface challenges, many of which arise from material defects at semiconductor surfaces, include signal attenuation in waveguides, light absorption in light emitting diodes, non-radiative recombination of carriers in solar cells, leakage (dark) current of photodiodes, and light reflection at solar cell interfaces for instance.

Efficient surface passivation of germanium nanostructures with 1% reflectance.

Germanium (Ge) is a vital element for applications that operate in near-infrared wavelengths. Recent progress in developing nanostructured Ge surfaces has resulted in >99% absorption in a wide wavelength range (300-1700 nm), promising unprecedented performance for optoelectronic devices. However, excellent optics alone is not enough for most of the devices (e.

Reusable radiochromic hackmanite with gamma exposure memory.

Radiochromic films are used as position-sensitive dose meters in medical physics and radiation processing. The currently available films like those based on lithium-10,12-pentacosdiynoate or leucomalachite green are either toxic or non-reusable, or both. There is thus a great need for a sustainable solution for radiochromic detection.

The structural origin of the efficient photochromism in natural minerals.

SignificanceNatural photochromic minerals have been reported by geologists for decades. However, the understanding of the photochromism mechanism has a key question still unanswered: What in their structure gives rise to the photochromism's reversibility? By combining experimental and computational methods specifically developed to investigate this photochromism, this work provides the answer to this fundamental question. The specific crystal structure of these minerals allows an unusual motion of the sodium atoms stabilizing the electronic states associated to the colored forms.

Atomic-Scale Modification of Oxidation Phenomena on the Ge(100) Surface by Si Alloying.

Properties of Ge oxides are significantly different from those of widely used Si oxides. For example, the instability of GeO at device junctions causes electronic defect levels that degrade the performance of Ge-containing devices (e.g.