Simulations, Practical Limitations, and Novel Growth Technology for InGaN-Based Solar Cells

Abstract

Indium gallium nitride (InGaN) alloys exhibit substantial potential for high-efficiency photovoltaics. However, theoretical promise still needs to be experimentally realized. This paper presents a detailed theoretical study to provide guidelines to achieve high-efficiency InGaN solar cells. While the efficiency of heterojunction devices is limited to ∼11%, homojunction devices can achieve suitable efficiencies, provided that highly p-type-doped InGaN layers and thick, single-phase InGaN films can be grown. Thus, we have developed a novel growth technology that facilitates growth of p-type nitride films with greatly improved hole concentration and growth of InGaN without phase separation, offering promise for future high-efficiency InGaN solar cells.

Polarization-Engineered InGaN/GaN Solar Cells: Realistic Expectations for Single Heterojunctions

“…[29], [30]. Due to the lack of experimental data for the minority carrier lifetime of InGaN alloys, the realistic and widely used [6], [7], [9], [10], [21], [22] in theoretical studies in InGaN-based solar cells value of 1 ns was assumed. In the simulations, the effect of radiative and Auger recombination is also considered.…”

III–V Multijunction Solar Cell Integration with Silicon: Present Status, Challenges and Future Outlook

“…Utilizing p-GaN/n-In x Ga 1-x N heterojunction is one of the ways to avoid the use of p-doped In x Ga 1-x N material, wherein the GaN layer also serves as a window layer and reduces the surface recombination (Brown et al 2010). However, theoretical efficiency of such GaN/ InGaN heterojunction is limited to 11% for 1J devices due to the polarization effects, which impede the carrier collection (Fabien et al 2014). Hence, homojunction devices would be essential to achieve higher efficiencies because employing p-i-n structures could eliminate the polarization effects.…”

“…InGaN based p-i-n solar cells with InGaN as the intrinsic layer between GaN and with graded indium composition up to 50% could lead to theoretical efficiency of 18.53% under AM1.5 (Mahala et al 2013). InGaN homojunctions with indium-rich, highly p-doped and thick bulk layers with no phase separation would be essential for the success of InGaN solar cells (Fabien et al 2014). Utilizing metal modulated epitaxy (MME), wherein the metal shutters are modulated with a fixed duty cycle under constant nitrogen flux, is a promising approach.…”

“…This technique allows for control of the kinetics of Mg incorporation, while using low substrate temperature for growth, thus offering great potential to overcome both ptype doping and phase-separation limitations in In-rich InGaN. InGaN material with up to 66% In content, good crystallinity and rms roughness of 0.76 nm was demonstrated using this MME growth approach (Fabien et al 2014). Further development of high-quality In-rich InGaN material would be crucial for realizing InGaN/Si tandem solar cells in the future.…”

Core–shell GaN–ZnO moth-eye nanostructure arrays grown on a-SiO2/Si (1 1 1) as a basis for improved InGaN-based photovoltaics and LEDs

“…These alloy systems are now projected to also provide a platform for the development of novel multi-junction photovoltaics (PVs) having a direct tunable bandgap with an unparalleled fit to the solar spectrum combined with a relatively high carrier mobility and drift velocity. They also offer the capacity for operation under the demanding temperature and radiation requirements of concentration [2,3]. External quantum efficiencies reported up till now, however, have been rather disappointing [3,4].…”