The effect of ammonia partial pressure on the growth of semipolar (11-22) InGaN/GaN MQWs and LED structures
Document Type
Article
Publication Date
5-1-2023
Abstract
This paper presents the effect of ammonia partial pressure at a relatively low fixed V/III (-765) growth at-mosphere on the growth of multi-quantum well (MQW) structures and the light emitting diode (LED) emission wavelength. At fixed V/III ratio, ammonia partial pressure together with the consequent group III partial pres-sures are shown to influence the growth of InGaN/GaN MQWs in term of growth rate and the indium incor-poration for the quantum well. It is also observed that the growth of InGaN quantum well (QW) behaves differently as compared to GaN quantum barrier (QB) at low V/III ambient. For the growth of InGaN QW, the data collected shows the existence of threshold point for ammonia partial pressure of-300 Pa. In the regime below the threshold value, the decomposition of InGaN due to severe dissociation of In-N bonds caused the growth rate to be extremely low. As the ammonia partial pressure increases above the threshold value, the growth rate of InGaN QW increases sharply together with an improvement in indium incorporation, as proven by the XRD and (11-24) asymmetric reciprocal space mapping (RSM) results. The XRD result is consistent with the atomic force microscopy (AFM) results. As the partial pressures increases, the RMS and peak-to-valley roughness increases which is credited to the increment in indium incorporation. Furthermore, ``needle-like'' structures can be observed over all samples when the MQWs were grown with limited ammonia partial pressure. During the growth for the LED structure with thin layers of InGaN/GaN, the partial pressure of ammonia became a domi-nating factor in the formation of well-abrupt layer interfaces. Through the XRD and room-temperature photo-luminescence (RTPL) results, it is shown that abrupt layers can be formed at higher ammonia partial pressures, while indium clusters tend to form at a lower partial pressure, which are most probably due to the insufficient N concentration, while the electroluminescence (EL) results were consistent as well. Therefore, it is once again confirmed that the performance of the InGaN/GaN LED is highly governed by the partial pressures of the ammonia.
Keywords
Semipolar, InGaN, GaN MQW, Ammonia partial pressure, Growth rate, Threshold
Divisions
mechanical,PHYSICS
Funders
Strategic Research Fund - Malaysia Ministry of Science, Technology and Innovation (MOSTI) (MOSTI005-2021SRF),Collaborative Research in Engineering, Science and Technology Center (CREST) (PV015-2015) ; (PV007-2019/T13C2-17)
Publication Title
Materials Science and Engineering B-Advanced Functional Solid-State Materials
Volume
291
Publisher
Elsevier
Publisher Location
RADARWEG 29, 1043 NX AMSTERDAM, NETHERLANDS