Spectral characterization of Mg₂Si pn ‐junction diode depending on RTA periods

Abstract

We have studied the effect of thermal annealing periods on the optoelectrical properties of Mg2Si pn ‐junction diodes fabricated by a conventional thermal diffusion process of Ag acceptor. The Au/Ag/n ‐Mg2Si (carrier concentration = 2 × 1015cm‐3, resistivity = 5‐10 Ωcm) substrate was annealed at 550 °C in the Ar‐atmosphere using a rapid thermal annealing (RTA) furnace. The annealing periods were varied between 2 and 10 minutes. Clear rectifying behavior of J ‐V characteristics was observed for the diodes annealed for more than 2 minutes. Spectral responsivity from the photon energy threshold of approximately 0.6 eV was demonstrated with the Mg2Si pn ‐junction diodes under the zero bias condition at room temperature. The maximum intensity of spectral responsivity was increased with decrease the annealing period. The spectral responsivity of the diode with the RTA periods of 4 minutes was approximately 4 times higher than that of 10 minutes annealed one. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Observation of pn-junction depth in Mg2Si diodes fabricated by short period thermal annealing

“…The annealing temperature and period were 480 °C and 1 min, respectively. There is no significant change in both morphology and shape of Au electrode before and after annealing as similar to our previous reports [12]. Figs.…”

“…The photosensitivity of the diode is improved by making the shallower pn-junction and the ring electrode in place of the opaque circular electrode [12,13]. However, those reported diodes had deep pn-junction more than 75 µm, because of the high thermal diffusion temperature (550 ℃) and the relatively long annealing time (4 min) compared with the high diffusivity of Ag in Mg2Si [11].…”

“…The band gap energy is able to control as far as 0.3 eV by making alloy compound with Mg2Si and Mg2Sn [9][10][11]. Therefore, Mg2Si and its alloy compounds are expected to be utilized for the infrared photodetector with the cut-off wavelength between 2 and 4 µm [7,12].…”

Fabrication and characterization of Mg₂Si pn-junction Photodiode with a ring electrode

“…The diode was fabricated by rapid thermal diffusion of Ag dopant into a high purity n-type Mg2Si substrate. Although the diode showed a photoresponsivity with threshold photon energy at approximately 0.6 eV, its intensity was pretty weak, since the diode had an opaque Au-circular electrode over the pn-junction region and most of the incident light was blocked by the electrod [11,10]. In this study, we report the fabrication and characterization of Mg2Si pn-junction photodiode with a ring electrode and a SiO2 passivation layer by means of a lift-off photolithography process.…”

Fabrication of Mg2Si pn-junction photodiode with shallow mesa-structure and ring electrode

“…Recently, we have reported Mg2Si pn-junction photodiodes (PD) fabricated by the thermal diffusion of Ag dopant into the n-type Mg2Si substrate and their clear photoresponse below 2 μm [5][6][7][8]. However, their sensitivity is needed to improve for practical device applications.…”