Epitaxial growth and electrical characterization of germanium

Lâm

et al. 2017

Sci Rep

Radial junction solar cells with vertically aligned wire arrays have been widely studied to improve the power conversion efficiency. In this work, we report the first Ge nanopillar solar cell. Nanopillar arrays are selectively patterned on p-type Ge (100) substrates using nanosphere lithography and deep reactive ion etching processes. Nanoscale radial and planar junctions are realized by an n-type Ge emitter layer which is epitaxially grown by MOCVD using isobutylgermane. In situ epitaxial surface passivation is employed using an InGaP layer to avoid high surface recombination rates and Fermi level pinning. High quality n-ohmic contact is realized by protecting the top contact area during the nanopillar patterning. The short circuit current density and the power conversion efficiency of the Ge nanopillar solar cell are demonstrated to be improved up to 18 and 30%, respectively, compared to those of the Ge solar cell with a planar surface.

Section: Resultsmentioning

confidence: 99%

Ge nanopillar solar cells epitaxially grown by metalorganic chemical vapor deposition

Lâm

et al. 2017

Sci Rep

“…Furthermore, the epitaxial growth approach using the IBuGe source could contribute to the well‐defined p‐n junction with precisely controlled doping profile and layer thickness. [ 36 ] But, it is worth noting that the high doping level of n‐ and p‐type Ge layers using the IBuGe source remains a principal bottleneck to form high‐quality epitaxial Ge p‐n junction. The undoped Ge layer in absence of an additional dopant has been reported as an n‐type Ge layer with background doping level of ≈6 × 10 18 cm −3 .…”

Section: Introductionmentioning

confidence: 99%

Ultrathin Flexible Ge Solar Cells for Lattice‐Matched Thin‐Film InGaP/(In)GaAs/Ge Tandem Solar Cells

Moon,

Kim,

Kim

et al. 2023

Solar RRL

Ultrathin Ge single‐junction (1J) solar cells transferred onto a flexible substrate are envisioned to open up a novel lattice‐matched thin‐film InGaP/(In)GaAs/Ge tandem solar cell for enabling highly efficient, low‐cost, and light‐weight flexible devices. The ultrathin Ge 1J solar cell structures are epitaxially grown onto a GaAs substrate via a low‐pressure metal–organic chemical vapor deposition system using an isobutylgermane metalorganic source as a Ge precursor. A simple and fast epitaxial lift‐off method allows the epi structures to transfer onto the flexible substrates, by which 2 inch wafer‐scale flexible ultrathin Ge 1J solar cells with the mechanical stability under bending test (R = 12.5 mm) are fabricated. Their maximum power conversion efficiency (5.40%) is achieved with the optimum thickness of Ge p‐n junction as well as a delta‐doping technique that utilizes the multiple cycles of Ga‐dopant injection and halt during the growth of thick p‐Ge base layer. The power‐to‐weight ratio value of the ultrathin Ge 1J solar cells is 56.65 times higher than that of bulk‐type Ge solar cells, holding great potential to be used for the power sources of unmanned aerial vehicles as well as the portable and wearable devices.

Письма В Журнал Технической Физики

“…На германии впервые было обнаружено образование поверхностных периодических структур в результате воздействия мощного импульсного лазерного излучения [8][9][10]. Кристаллический германий со структурой алмаза, оптические свойства которого нами изучались ранее [11][12][13], является одним из наиболее исследованных материалов, технология получения которого достигла крайне высокой степени чистоты [14,15]. В связи с применением германия в фотоэлектронных устройствах различного назначения (фотоэлектрические преобразователи, фотоприемники) возникает необходимость исследования модифицирования поверхности материала более подробно.…”

unclassified

Лазерное Травление Германия

Железнов¹,

Малинский²,

Миколуцкий³

et al. 2021

When studying the scanning of the polished surface of germanium single crystals by focused pulse-frequency radiation of an ultraviolet Nd:YAG laser, it was found that at subthreshold energy densities (at E ͠͠ 0.5–1.15 J/cm2), in the absence of noticeable traces of crater formation, laser etching was observed. It is assumed that the centers of ablation nucleation are dislocations coming out on the crystal surface.