Interdigitated back‐contact double‐heterojunction GaInP/GaAs solar cells

Abstract

Interdigitated back‐contact (IBC) silicon solar cells are coming of age, but the potential of IBC configurations for compound semiconductor solar cells is yet to be explored. We outline an approach to generalize the diffusion‐driven charge transport (DDCT) method, previously studied for IBC light‐emitting diodes, to develop DDCT solar cells, enabling an IBC double‐heterojunction structure. In particular, we simulate and compare the electrical performance of a GaInP/GaAs DDCT solar cell with an ideal one‐dimensional reference cell to establish how the lateral dimensions of the DDCT structures affect their operation. Also, the suitability of the DDCT solar cells for concentration photovoltaics is explored. The results show that the DDCT solar cells with a finger pitch of approximately 10μm can match and even outperform the ideal reference structure under the AM1.5G solar spectrum, due to reduced Shockley‐Read‐Hall recombination. At high solar concentrations, the performance of the smallest pitch DDCT structure is essentially identical with the reference structure up to 100 suns. This suggests that combining the benefits offered by the IBC design with compound semiconductors could allow the development of an entire family of more efficient solar cells.

Back‐Contacted Carrier Injection for Scalable GaN Light Emitters

“…[ 19 ] We have previously suggested diffusion‐driven charge transport (DDCT) as a possible alternative for the DHJ based current injection method to overcome its limitations. [ 20,21 ] Following the originally computational introduction of the DDCT method, III‐nitride diffusion injected light emitting diodes (DILEDs) [ 22,23 ] were fabricated and characterized. In spite of being the first experimental demonstration that bipolar diffusion can transport electrons and holes into the active region located outside the pn‐junction and a proof of the DDCT concept, DILED suffered from parasitic yellow luminescence emission, inferior injection efficiency due to the highly n‐doped layer between the MQW and p‐type GaN, and high resistivity metal contacts.…”

Back-Contacted GaInP/GaAs LED Structures by Ex-Situ Dopant Redistribution

“…1(c) and (d) and excludes the contact pads and the thick-substrate region for simplicity. A more detailed description of the model can be found in, for example, [7], [8].…”

“…Fabrication of compound semiconductor-based DDCT devices is not established due to the unconventional device structures and lack of appropriate lateral doping techniques. So far, experimental studies on DDCT-LEDs have focused merely on GaN devices [10], [21], [22], [23], [24], while GaAs devices have been considered only theoretically [7], [8], [9]. The first report of GaN-based DDCT-LEDs by Riuttanen et al [10] demonstrated the fundamental principle of DDCT by injecting holes into AR through an n-GaN layer.…”

“…1(a), are enabled by ex-situ dopant redistribution utilizing Zn diffusion from patterned p+-GaAs layer. The control structure is specifically designed to validate the presence of diffusion doping in the DDCT structures: the p-n junction of the control structure is completely misaligned with the AR, and the only way to transform the control device into a properly working LED is by redistributing the highly diffusive Zn dopants to form a laterally doped DDCT device studied in [7] and [8]. The fabrication process for the devices is almost identical and differs only in the silicon nitride encapsulation and diffusion annealing which are only performed on the DDCT structures.…”