Open AccessInductively coupled CH 4 /H 2 plasma etching process for mesa delineation of InAs/GaSb type‐II superlattice pixels
Author(s) -
Das Sona,
Das Utpal
Publication year - 2019
Publication title -
micro and nano letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.25
H-Index - 31
ISSN - 1750-0443
DOI - 10.1049/mnl.2018.5549
Subject(s) - superlattice , photodiode , materials science , dark current , etching (microfabrication) , optoelectronics , inductively coupled plasma , diode , biasing , plasma , optics , voltage , photodetector , nanotechnology , physics , layer (electronics) , quantum mechanics
An inductively coupled C H 4 / H 2 plasma etching process for delineation of InAs/GaSb type‐II superlattice pixels is presented. An optimised C H 4 / H 2 etch recipe without alternate O 2 plasma cleaning step showed an etch rate as high as 0.11 μm/min that results in smooth vertical sidewalls for the type‐II superlattice pixel arrays with 10 μm pitch size and 2.4 μm deep trenches. At 70 K, the dark current density for the mesa etched + SU‐8 polymer passivated type‐II superlattice photodiodes was found to be 0.11 A/cm 2 at an applied reverse bias voltage of 0.2 V. The activation energy of 13 meV obtained from the Arrhenius plot and a variable area diode array technique showed that the measured dark current is mainly attributed to bulk tunnelling current. This technique of mesa delineation for the type‐II superlattice pixel arrays with small pitch size is a viable option in realising next‐generation infrared focal plane arrays.