Growth and properties of digitally-alloyed AlGaInP by solid source molecular beam epitaxy

Abstract

Digital alloying using molecular beam epitaxy (MBE) was investigated to produce AlGaInP quaternary alloys for bandgap engineering useful in 600-nm band optoelectronic device applications. Alternating Ga 0.51 In 0.49 P/Al 0.51 In 0.49 P periodic layers ranging from 4.4 monolayers (ML) to 22.4 ML were used to generate 4,000-Å-thick (Al 0.5 Ga 0.5 ) 0.51 In 0.49 P quaternary materials to understand material properties as a function of constituent superlattice layer thickness. High-resolution x-ray diffraction (XRD) analysis exhibited fine satellite peaks for all the samples confirming that digitally-alloyed (Al 0.5 Ga 0.5 ) 0.51 In 0.49 P preserved high structural quality consistent with cross-sectional transmission electron microscopy (X-TEM) images. Low-temperature photoluminescence (PL) measurements showing a wide span of luminescence energies ϳ170 meV can be obtained from a set of identical composition digitally-alloyed (Al 0.5 Ga 0.5 ) 0.51 In 0.49 P with different superlattice periods, indicating the bandgap tunability of this approach and its viability for III-P optoelectronic devices grown by MBE.

Optical Characterization of AlAsSb Digital Alloy and Random Alloy on GaSb

“…The DA sample also exhibits a smaller bandgap energy than the RA sample, likely due to the ordering effect [22]. Similar results have been observed in other quaternary materials, the DA growths of which exhibit a relatively small bandgap energy, within 2-3% of that of the RA growth [15,23]. On the other hand, DL peaks display an anomalous temperature dependence with respect to the E X peak, which will be discussed later in the text.…”

Atomic variations in digital alloy InGaP/InGaAlP multiple quantum wells due to thermal treatment

“…[7][8][9][10][11][12] When the InGaP/InGaAlP MQWs are grown using the DA method with a combination of InGaP and InAlP ternary alloys, nonradiative defects, which decrease the device characteristics of the LEDs, are generated in the strained InGaP/ InGaAlP MQWs. 13,14) The device performance of InGaP/ InGaAlP-based LEDs can be improved by thermal annealing to enhance the quality of DA materials. 15,16) Because the optical properties of MQWs are significantly affected by the atomic-scale microstructural and chemical properties, many studies concerning the microstructural properties of MQWs have been conducted.…”

Aluminum Gallium Nitride Alloys Grown via Metalorganic Vapor-Phase Epitaxy Using a Digital Growth Technique

“…1 This has been a very effective means of growing ternary and quaternary alloys in a number of material systems including the arsenides, 2 phosphides, 3 antimonides, 4 and nitrides; [5][6][7] for example, within the III-nitride system, a digital aluminum gallium nitride (Al x Ga 1Àx N) alloy consists of the repetition of m monolayers of AlN followed by n monolayers of GaN, represented as (AlN) m (GaN) n . From the growth perspective, digital techniques have presented several advantages over conventional random alloy growth.…”

“…7 As expected, along with the composition, the electronic properties of the material can also be finely tuned using this technique. 3,5 For the most part, digital techniques are more commonly studied in molecular beam epitaxy (MBE) rather than metalorganic vapor-phase epitaxy (MOVPE). In MBE, the technique is very attractive due to the fact that the composition is dependent on shutter timing not incident flux.…”