M. Jalonen

All-solid-source molecular beam epitaxy for growth of III–V compound semiconductors

Abstract All-solid-source molecular beam epitaxy (SS-MBE) is a novel variant of MBE. It allows for toxic-gas-free growth of III–V compound semiconductors, including phosphides. We have examined the quality of SS-MBE-grown phosphorus containing heterostructures and laser diodes. The results discussed in this article show that state-of-the-art quantum well (QW) materials and lasers, covering a wide range of bandgaps from red to infrared, can be prepared by SS-MBE.

Effects of rapid thermal annealing on GaInP/AlGaInP lasers grown by all-solid-source molecular beam epitaxy

We have examined the influence of rapid thermal annealing on the performance characteristics of GaInP/AlGaInP quantum well lasers which were grown by all-solid-source molecular beam epitaxy. It was found that when the laser structures were annealed the threshold current densities of the lasers decreased significantly. This improvement in lasing performance could be associated with the possibility that annealing removed nonradiative recombination centers from the quantum wells. The emission wavelength, differential quantum efficiency, and characteristic temperature were not affected to any remarkable extent, indicating that the interdiffusion of group-III elements did not damage the structures.

All solid source molecular beam epitaxy growth of strained‐layer InGaAs/GaInAsP/GaInP quantum well lasers (λ=980 nm)

We report on the growth of 980‐nm strained‐layer InGaAs/GaInAsP/GaInP separated confinement quantum well lasers using all solid source molecular beam epitaxy. Valved cracker cells were employed for both phosphorus and arsenic. Fabricated lasers exhibited excellent performance that is comparable to similar lasers grown by gas source molecular beam epitaxy in our laboratory. A maximum output power of 450 mW and over 250 mW in single mode operation was achieved for ridge waveguide lasers with AR/HR coated facets.

Monolithic super-bright red resonant cavity light-emitting diode grown by solid source molecular beam epitaxy

Monolithic super-bright resonant-cavity light-emitting diode operating at /spl lambda/=663 nm has been developed. The diode consisted of a 1/spl lambda/-thick AlGaInP active region sandwiched between AlAs-AlGaAs distributed Bragg reflectors. The device structure was grown by solid source molecular beam epitaxy. The current aperture of the emitter was created by lateral selective wet thermal oxidation. A record-high peak wall-plug efficiency of 2.2% and a continuous-wave output power of 1.4 mW were attained without heatsinking at room temperature from a diode having a diameter of 80 /spl mu/m. The emission linewidth was as narrow as 4.5 nm.

GaInP/GaAs cascade solar cells grown by molecular beam epitaxy

First results for molecular beam epitaxy (MBE) grown Ga/sub 0.51/In/sub 0.49/P/GaAs cascade solar cells are presented. The structures were prepared by both solid-source (SS) MBE and gas-source (GS) MBE. The tunnel diodes between the subcells were grown by using the standard MBE dopants (silicon and beryllium) but dopant diffusion related degradation of the cell characteristics was not observed. For the best SSMBE structure, a conversion efficiency of 21.1% was measured at AM0 for a 1/spl times/1 cm/sup 2/ cell. For the GSMBE structures, the best AM0 conversion efficiency was 20.8% for a 2/spl times/2 cm/sup 2/ device. In addition, the first MBE results for advanced Al/sub 0.51/In/sub 0.49/P/Ga/sub 0.51/In/sub 0.49/P-based tunnel diodes are presented.

Unipolar avalanche multiplication phenomenon in multiquantum well structures

Unipolar electron impact ionization and multiplication in photodiodes consisting of GaAs/AlGaAs multiquantum well heterostructures have been observed. In these diodes, electrons generated by photon absorption and accelerated in the barrier regions scatter bound electrons from the donor‐doped GaAs wells. Gain‐per‐well of 1.13±0.05 and total gain of 100 for the multiplication region have been demonstrated. The photodiodes exhibit high dark current which arises from thermionic emission and tunneling of electrons out of the wells.

Solid source molecular beam epitaxy growth of GaInP/AlGaInP heterostructures and 600-nm-range quantum well laser diodes

We have studied the growth of (Al/sub x/Ga/sub 1-x/)/sub 0.51/In/sub 0.49/P quaternary alloy and GaInP/AlGaInP heterostructures using solid, elemental phosphorus in a valved cracking cell by molecular beam epitaxy. The results obtained have been applied for the growth of strained-layer quantum well laser structures emitting in the red-light region. In order to further assess the quality of our materials, the grown laser structures have been processed into laser diodes that have been characterized. The measured threshold current densities of the 1 mm long as-cleaved broad-area laser diodes were 385 A/cm/sup 2/ and 820 A/cm/sup 2/ at 680 nm and 633 nm, respectively. To the best of our knowledge these values are the lowest reported threshold current densities for SSMBE grown lasers in this wavelength range. A high T/sub 0/ of 113 K was obtained for double-QW in the temperature interval of 20/spl deg/C-90/spl deg/C. All these results clearly demonstrate that state-of-the-art 600-nm-range laser diodes can be prepared using only solid sources.

Solid source MBE for phosphide-based devices

Phosphorus-based materials are of great importance for many advanced optoelectronic and electronic devices. The most common techniques used for growing phosphorus containing epitaxial structures are MOCVD, GSMBE and CBE. All these growth methods use highly toxic hydrides as group-V sources. As environmental regulations, safety precautions and cost effectiveness are important issues in compound semiconductor business, there is an urge for a simpler and cheaper growth technique. Molecular beam epitaxy using solid sources for both phosphorus and arsenic (SSMBE) would be the simplest choice. However, the problematic physical properties of phosphorus have hampered the use of SSMBE until recently. The new valved cracker technology has overcome the problems associated with the use of solid phosphorus and SSMBE has matured to the level that state-of-the-art phosphorus-based materials and devices can be produced. In this paper, we review some of our results for SSMBE grown phosphide-based devices. These include strained-layer InGaAsP/InP SCH-MQW and strain-compensated InAsP/InGaP/InP MQW lasers emitting at 1.3 /spl mu/m, strained-layer InGaAs/InGaAsP/GaInP QW lasers for 980 nm and 905 nm, 680 nm strained-layer GaInP/AlGaInP QW lasers, and InGaAs/InP HBTs.

Bonding of indium phosphide layers on silicon substrates

Indium phosphide layers were bonded on silicon substrates by indium antimonide and gold based eutectic alloys. Although the thermal expansion coefficient of InSb is the same as that of InP, the bonding did not succeed with this material. When using Au based eutectic alloys, the bonding was successful. Large areas could be bonded homogeneously, and InP solar cells were processed on these structures with good characteristics. Because the solar cell is a minority carrier device, its characteristics are significantly worsened by the dislocations which reduce the minority carrier diffusion length. The bonding method has been applied for transferring InP layers on Si to avoid the formation of misfit dislocations at the interface.<<ETX>>

Oxide-confined AlGaInP/AlGaAs visible resonant cavity light-emitting diodes grown by solid source molecular beam epitaxy

Summary form only given. This paper reports the growth, fabrication, and characterization of the first solid source molecular beam epitaxially (SSMBE)-grown visible resonant cavity LEDs. The epitaxial layers were grown by SSMBE on (100) Si-doped GaAs (2-inch) wafers.