Molecular beam epitaxy grown $0.6eV$ $n∕p∕n$ $InPAs∕InGaAs∕InAlAs$ double heterostructure thermophotovoltaic devices using carbon as the $p$-type dopant

Beryllium (Be) has been previously shown to be an adequate $p$-type dopant for molecular beam epitaxy (MBE) grown $0.6eV$ $n∕p∕n$ $InGaAs∕InPAs$ double heterostructure thermophotovoltaic (TPV) devices. However, due to environmental, safety, and health operational concerns caused by airborne exposure to Be during cleaning operations in a MBE system, carbon (C) was investigated as a $p$-type dopant substitute. However, due to the amphoteric nature of C, it incorporates on the group-III site in InGaAsP material with high P content, making it $n$ type. Therefore, to grow the $n∕p∕n$ InGaAs double heterostructure TPV device, InAlAs was developed as the back surface field (BSF). By using C as the $p$-type dopant and InAlAs as the BSF, MBE grown $0.6eV$ $n∕p∕n$ $InPAs∕InGaAs∕InAlAs$ double heterostructure TPV devices were successfully made. The demonstrated room temperature reverse saturation current density $(j0)$ value from this MBE grown device was $∼9μA∕cm2$⁠. This $j0$ value was only three times larger than the previous best MBE grown $0.6eV$ $n∕p∕n$ $InGaAs∕InPAs$ double heterostructure TPV device using Be as the $p$-type dopant. Internal quantum efficiency evidence suggested that, by improving the base/BSF interface for the device having the InAlAs BSF and C $p$-type doping, $j0$ values lower than the previous best MBE grown TPV material were possible. Therefore, C was found to be a promising alternative to Be in $0.6eV$ $n∕p∕n$ $InPAs∕InGaAs∕InAlAs$ double heterostructure TPV devices.