Open AccessHigh Figure‐of‐Merit Gallium Oxide UV Photodetector on Silicon by Molecular Beam Epitaxy: A Path toward Monolithic Integration
Author(s) -
Mukhopadhyay Partha,
Hatipoglu Isa,
Sakthivel Tamil Selvan,
Hunter Daniel A.,
Edwards Paul R.,
Martin Robert W.,
Naresh-Kumar Gunasekar,
Seal Sudipta,
Schoenfeld Winston V.
Publication year - 2021
Publication title -
advanced photonics research
Language(s) - English
Resource type - Journals
ISSN - 2699-9293
DOI - 10.1002/adpr.202000067
Subject(s) - responsivity , molecular beam epitaxy , materials science , optoelectronics , figure of merit , wafer , substrate (aquarium) , dark current , gallium , photodetector , thin film , band gap , epitaxy , nanotechnology , layer (electronics) , oceanography , geology , metallurgy
A high figure‐of‐merit UV‐C solar‐blind photodetector (PD) fabricated from thin‐film beta‐gallium oxide (β‐Ga 2 O 3 ) grown on n ‐Si substrates by plasma‐assisted molecular beam epitaxy is demonstrated. Film growth sequences for nucleation of Ga 2 O 3 on (100)‐ and (111)‐oriented Si substrates are developed, and the influence of crucial growth parameters is systematically investigated, namely, substrate temperature, oxygen flow rate, and plasma power on the functional properties of the PDs. The PDs show an ultra‐high responsivity of 837 A W −1 and a fast ON/OFF time below 4 ms at −5 V. In addition, they display strong rectifying properties and a sharp cutoff below 280 nm with the average responsivities between 10 and 80 A W −1 , a detectivity on the order of 10 10 Jones, and rise/fall times between 4 and 500 ms. High photoconductive gain is likely to be due to the mid‐bandgap donor/acceptor defect levels, including oxygen vacancies in the form of self‐trapped holes. It is demonstrated that these defect levels can be modified by controlling the growth conditions, thereby allowing for tailoring of the PD characteristics for specific applications. The methodology represents a cost‐effective solution over homoepitaxial approaches, with characteristics that meet or exceed those reported previously, offering new possibilities for on‐wafer integration with Si opto‐electronics.