Low-voltage-operation avalanche photodiode based on n-gallium oxide/p-crystalline selenium heterojunction

Abstract

In this study, we demonstrate the avalanche multiplication phenomenon in a crystalline-selenium (c-Se)-based heterojunction photodiode. The carrier injection from an external electrode, which is considered to be the major factor contributing to dark current at a high electric field, was significantly decreased by employing a thin n-type Ga2O3 layer with a high hole-injection barrier. The fabricated Ga2O3/c-Se diode exhibited extremely high external quantum efficiency of over 100% in the short-wavelength region at a relatively low reverse-bias voltage of ∼20 V. Furthermore, Sn-doping of the Ga2O3 layer increases the carrier concentration; hence, the resulting device has a lower threshold voltage for avalanche multiplication.

A Strategic Review on Gallium Oxide Based Deep‐Ultraviolet Photodetectors: Recent Progress and Future Prospects

“…For gallium oxide, avalanche photodiodes have been fabricated with the use of heterostructures. [ 128 ] Mahmoud [ 69 ] has fabricated avalanche photodetector based on β‐Ga 2 O 3 /SnO 2 bilayer heterostructure with an avalanche gain of 1.7 × 10 5 at reverse bias of −5.5 V. The SnO 2 layer was deposited by RF Sputtering while the β‐Ga 2 O 3 layer was performed by a cation exchange mechanism to reduce the lattice mismatch between the two layers at the interface between them. Figure a shows the energy band diagram elucidating the mechanism of APD at a forward and reverse bias.…”

“…After a certain applied bias, the photogenerated carriers acquire high enough velocity under the action of the high electric field to cause impact ionization and hence cause a rapid increase in the photocurrent. [127][128] The other mechanism that is ascribed for the high photoconductive gain is the formation of STHs and their subsequent lowering of effective Schottky barrier height. These STHs are thought to occur in the gallium oxide material itself as opposed to the hole trapping by the defect states at the Schottky metal contact.…”

Functional Oxides for Photoneuromorphic Engineering: Toward a Solar Brain

“…The solaristor (a portmanteau of SOLAR cell transISTOR) is the compact two terminal self-powered phototransistor (with a normallyoff state), or in other words, a solar cell and a memristor in series (Fig. 8 (a) Conventional phototransistors exhibit photoconductive gain, which is not seen in photodiodes (except avalanche photodiodes [569] , [570] ), and results in external quantum efficiencies (EQEs) well over 100%. For example, for an image sensor pixel in low lighting, photoconductive gain in the phototransistor enables higher EQEs than the photodiode-based pixel [571] .…”

Enhanced image sensing with avalanche multiplication in hybrid structure of crystalline selenium photoconversion layer and CMOSFETs

“…The advantage is that polycrystalline Se can be fabricated on almost all types of substrates and the disadvantage is that crystal grains must be controlled to flatten the surface of the c-Se layer to obtain high-quality images. Previously, employing a wide-bandgap n-type semiconducting gallium oxide (Ga 2 O 3 ) as a hole blocking layer, we reported avalanche multiplication at a low reverse bias voltage in a c-Se-based photodiode fabricated on a glass substrate, which exhibited extremely high external quantum efficiency (EQE) of more than 100% 22 .…”