The development of (InGa)As thermophotovoltaic cells on InP using strain-relaxed In(PAs) buffers

• Published in: Journal of crystal growth 2008-07, Vol.310 (15), p.3453-3458
• Main Authors: Cederberg, J.G., Blaich, J.D., Girard, G.R., Lee, S.R., Nelson, D.P., Murray, C.S.
• Format: Article
• Language: English
• Subjects: A3. Metal-organic chemical vapor deposition; Applied sciences; B2. Semiconducting III–V materials; B3. Infrared devices; Condensed matter: structure, mechanical and thermal properties; Defects and impurities: doping, implantation, distribution, concentration, etc; Electronics; Energy; Exact sciences and technology; Materials; Microelectronic fabrication (materials and surfaces technology); Natural energy; Photovoltaic conversion; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Solar cells. Photoelectrochemical cells; Solar energy; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2008.04.037

We have investigated thermophotovoltaic monolithic interconnected modules fabricated from In 0.68Ga 0.32As on InP using In(PAs) buffer layers to mitigate the lattice mismatch. The growth of these devices presented several challenges. For example, the n-type dopant Te forms a persistent surface-segregation layer on In(PAs) and (InGa)As layers, which unintentionally distributes Te into subsequently deposited layers. To solve this problem, we identified growth conditions that promote Te desorption from the InGaAs surface, thereby enabling the formation of sharp doping profiles. Another significant challenge involved In-rich surface defects, which form during In 0.68Ga 0.32As growth and act as shunt paths that severely reduce cell performance. To address this problem, we implemented pre-growth particle-control procedures that allow surface defect densities below 100 cm −2 to be obtained. Our progress allowed the demonstration of thermophotovoltaic cells producing 348 mV/junction open-circuit voltage with a fill factor exceeding 70%.