Abstract
In this dissertation, we investigate the fabrication and characterization of large-area planar-type InGaAs p-i-n short-wave infrared (SWIR) photodiodes (PDs) by using the rapid thermal diffusion (RTD) technique with spin-on dopant (SOD) source to form a p-type region of p-i-n diode. The absorption layers of 1.7-μm cutoff-wavelength PDs and 2.2-μm wavelength-extended PDs are In0.53Ga0.47As and In0.73Ga0.27As, respectively. In order to enhance the responsivity of PDs, the Si/Al2O3 or gallium-doped zinc oxide (GZO) /SiO2 bi-layers are used as the antireflective (AR) coating. The large-area planar-type 1.7-μm cutoff-wavelength InP/InGaAs/InP p-i-n PDs by using the RTD technique with ZPDC source are demonstrated. The 1.7-μm cutoff-wavelength PD exhibits a low dark-current density of 8.6 nA/cm2 at -10 mV, a high responsivity of 1.1 A/W at the wavelength of 1.55 μm, a high quantum-efficiency of above 90% in the wavelength range of 1.0-1.55 μm, and a sharp cutoff-wavelength of 1.65 μm. The large-area planar-type 1.7-μm cutoff-wavelength InP/InGaAs/InP p-i-n PDs by using the RTD technique with MgSiOx source are demonstrated. The electric and optical characteristics of 1.7-μm PD with Mg driven-in are comparable to that those of 1.7-μm PD with Zn driven-in. The 1.7-μm PD exhibits a low dark-current density of 4.0 nA/cm2 at -10 mV, a high responsivity of 1.1 A/W at the wavelength of 1.55 μm, a high quantum-efficiency of above 90% in the wavelength range of 1.0-1.55 μm, and a sharp cutoff-wavelength of 1.65 μm. The large-area planar-type 1.7-μm cutoff-wavelength InP/InGaAs/InP p-i-n PD by using the GZO transparent conducting oxide (TCO) as a lateral current-spreading layer for reduction in the lateral resistance of p-InP contact layer and improvement in the uniformity of spatial response are demonstrated. The GZO films deposited by e-gun evaporation with 400-°C post-annealing show a low sheet-resistance of 28 Ω/□, which is much lower than the 1-μm p-InP contact layer of ~300 Ω/□. The 1.7-μm PD with GZO layer exhibits a low dark-current density of 4.8 nA/cm2 at -10 mV and 68 nA/cm2 at -5 V, a high responsivity of 1.0 A/W at the wavelength of 1.55 μm, a high quantum-efficiency of 80-85% in the wavelength range of 1.0-1.55 μm, and a sharp cutoff-wavelength of 1.65 μm. In addition, the 1.7-μm PD with GZO layer exhibits a more uniform spatial-response under high optical-power illumination. It is attributed to the use of GZO film as a lateral current-spreading layer. The large-area planar-type 2.2-μm wavelength-extended InAsP/InGaAs/InAsP p-i-n PDs by using the RTD technique with ZPDC source are demonstrated. The 2.2-μm PD exhibits a low dark-current density of 8.2 μA/cm2 at -10 mV, a high responsivity of 1.25 A/W at the wavelength of 2.0 μm, a high quantum-efficiency of 80-85% in the wavelength range of 1.5~2.0 μm, and a sharp cutoff-wavelength of 2.2 μm.