Temperature and band gap dependence of GaAsBi p-i-n diode current–voltage behaviour

Abstract

The dark current characteristics of two series of bulk GaAsBi p-i-n diodes are analysed as functions of temperature and band gap. Each temperature dependent measurement indicates that recombination current dominates in these devices. The band gap dependence of the dark currents is also consistent with recombination dominated current for the devices grown at a common growth temperature, indicating that the presence of Bi does not directly adversely affect the dark currents. However, the devices grown at different growth temperatures exhibit a faster increase in dark current with decreasing device band gap, suggesting that a reduced growth temperature causes a reduction in minority carrier lifetime.

GaAsBi: From Molecular Beam Epitaxy Growth to Devices

“…This has implications for simultaneously maximizing the Bi content and the growth temperature, as required for the best device properties. [ 119 ] Maximal Bi content requires growth on the cusp of Bi droplet formation; however, for thicker devices, it is necessary to reduce the Bi flux and temperature to remain droplet free. It may be possible to use growth halts to crystallize excess Ga and desorb excess Bi.…”

“…Existing temperature‐limited Bi content predictions are all based on quasiequilibrium growth conditions [ 92,97,104 ] and exceeding these limits through nonequilibrium growth may lead to substantially reduced device dark currents. [ 119 ]…”

Effect of MBE growth conditions on GaAsBi photoluminescence lineshape and localised state filling

“…Of all the devices studied, G1B3 exhibited the largest localisation energies, E loc , at all excitation powers, indicating very low state filling. This suggests a short non-radiative lifetime, as expected from the low growth temperature used for this device 29 . Due to this low level of carrier filling, the band edge state distribution, G 1 , contributed a negligible proportion of the filled states compared to G 2 (equivalent to energies at and below 1.25 eV in Fig.…”

“…This observation agrees with a report by Richards et al . which concludes that the Bi content does not impact the dark currents and that only the growth temperature and band gap affect this characteristic 29 . The overall findings of this work, however, indicate that surface Bi coverage does impact the material quality and may be essential in mitigating the deleterious effects of low temperature growth.…”

GaAsBi: From Molecular Beam Epitaxy Growth to Devices

“…As droplets form due to Bi and/or Ga accumulation on the growing surface, they can nucleate tens or even hundreds of nm after the start of growth. This has implications for simultaneously maximising the Bi content and the growth temperature, as required for the best device properties [121] . Maximal Bi content requires growth on the cusp of Bi droplet formation; however, for thicker devices, it is necessary to reduce the Bi flux and temperature in order to remain droplet-free.…”