A High-Speed Au/In_0.53Ga_0.47As/InP Schottky Barrier Photodiode for 1.3–1.65 µm Photodetection

Abstract

With the advent of femtosecond laser pulses and light modulation in the tens of GHz frequency range, the development of high-speed photodetectors is necessary for microwave optical fiber communications at 1.30–1.65 [µm]. High-speed photodetectors have been fabricated mainly on GaAs using Schottky barrier structure for 0.80–0.90 [µm] and on In_0.53Ga_0.47As for 1.30–1.65 [µm] using p-i-n structure. In this paper, we propose a novel high-speed long wavelength Au/p⁺-n-In_0.53Ga_0.47As/n⁺-InP Schottky barrier structure to enhance the effective barrier height. The proposed Au/p⁺-n-In_0.53Ga_0.47As/n⁺-InP Schottky barrier photodiode structure requires the use of a very thin surface layer of p⁺-In_0.53Ga_0.47As on the n-In_0.53Ga_0.47As epitaxial layer grown on n⁺-InP substrate in order to enhance the effective barrier height. The significance of this new structure lies on its ability to increase the effective barrier height, and hence to overcome the problem of large dark current encountered in such a detector [1–2]. This approach for barrier height enhancement has been demonstrated previously in GaAs [3] and InGaAs Schottky diodes [4], and is used in our Au/In_0.53Ga_{0. 47}As/InP system for photodetector applications.