Makoto Kondo

CRYSTALLOGRAPHIC ORIENTATION DEPENDENCE OF IMPURITY INCORPORATION INTO III-V COMPOUND SEMICONDUCTORS GROWN BY METALORGANIC VAPOR PHASE EPITAXY

This article presents a comprehensive study of the dependence of impurity incorporation on the crystallographic orientation during metalorganic vapor phase epitaxy of III‐V compound semiconductors. We performed doping experiments for group‐II impurities (Zn and Mg), group‐VI impurities (Se and O), and a group‐IV impurity (Si form SiH4 and Si2H6). The host materials were GaAs, Ga0.5In0.5P, and (Al0.7Ga0.3)0.5In0.5P grown on GaAs substrates. We examined the doping efficiency on the surfaces lying between {100} and {111}A/B. Even though we grew epitaxial layers in a mass‐transport‐limited regime, the doping efficiency significantly depended on the orientation, indicating that the surface kinetics plays an important role in impurity incorporation. Comparing our results with other reports, we found that acceptor impurities residing on the group‐III sublattice and donor impurities residing on the group‐V sublattice, respectively, have their own distinctive orientation dependence. Si donors exhibit orientation d...

Crystal Orientation Dependence of Impurity Dopant Incorporation in MOVPE-grown III-V Materials

Abstract We investigated the crystal orientation dependence of impurity dopant incorporation in III–V compound semiconductors grown be metalorganic vapor phase epitaxy (MOVPE). Doping experiments were performed for group-II acceptors (Zn and Mg), a group-VI donor (Se), and a group-IV donor (Si from silane or disilane) into MOVPE-grown GaAs, Ga 0.5 In 0.5 P, and (Al 0.7 Ga 0.3 ) 0.5 In 0.5 P. The doping efficiency for each impurity was studied between (100) and (111)A/B faces. Comparing our results to previous reports, we found that there is a general rule in the orientation dependence of impurity incorporation, according to dopant groups. The group-II acceptors (Cd, Mg, and Zn), which reside on the group-III sublattice, are preferentially incorporated on the ( h 11)A face ( h ≥ 1) and, in many cases, incorporated less on the ( h 11)B face ( h ≥ 1) than on the (100) face. I n all materials, the Zn incorporation is most prominent on the (311)A face. In contrast, the group-VI donors, which reside on the group-V sublattice, are preferentially incorporated on the ( h 11)B face ( h ≥ 1) and incorporated less on the ( h 11)A face ( h ≥ 1) th an on the (100) face. Comparing to group-II and group-VI impurities, Si generally exhibits weak dependences. Based on rate limiting processes for the dopant incorporation, we constructed a model for the orientation dependence for the group-II and group-VI impurities, considering atomic bonding geometries between adsorbed impurity atoms and adsorption sites.

Dependence of carbon incorporation on crystallographic orientation during metalorganic vapor phase epitaxy of GaAs and AlGaAs

Abstract We studied the dependence of carbon (C) incorporation on the crystallographic orientation during metalorganic vapor phase epitaxy (MOVPE) of GaAs and AlGaAs. We performed C doping to GaAs grown with trimethylgallium (TMGa) and AsH 3 and Al 0.35 Ga 0.65 As grown with trimethylaluminum (TMAl), TMGa or triethylgallium (TEGa), and AsH 3 on the surface lying between (100) and (111) A/B. C and hole concentrations nearly coincided over the entire orientation range, showing that C is preferentially incorporated at As sites, irrespective of orientation. We found that the dependence of C incorporation on the orientation is more complex than previously thought. The dependence of carrier concentration on the AsH 3 partial pressure reflected the degree of C incorporation very well. Using simultaneous doping with C acceptors and Si donors, we fabricated lateral p-n junctions on patterned substrates composed of the (100) principal surface and (411)A/B sidewalls.

Origin of nonradiative recombination centers in AlGaInP grown by metalorganic vapor phase epitaxy

We report the first concrete evidence that oxygen causes nonradiative deep levels in (Alx Ga1–x)0.5In0.5P grown by metalorganic vapor phase epitaxy. We doped AlGaInP with O2 and investigated the oxygen and deep level concentrations by secondary ion mass spectroscopy and isothermal capacitance transient spectroscopy. We confirmed that oxygen causes the D3 (thermal activation energy: ET ≅ 1.0 e V for x = 0.7, nonradiative recombination center) and D2 (ET ≅ 0.46 e V) levels, which we previously found in undoped AlGaInP. We demonstrate that the oxygen and nonradiative deep level concentrations are significantly reduced at higher growth temperatures, higher PH3 partial pressures, and substrate offset from (100) toward [011].

Study on radiative efficiency in AlGaInP/GaInP double-heterostructures : influence of deep level in cladding layers

Abstract We have studied the recombination process of carriers in AlGaInP/GaInP double heterostructures grown by metalorganic vapor phase epitaxy using time-resolved photoluminescence. We found that interfacial recombination is a major process in our samples. We have also studied the influence of the deep-level concentration in AlGaInP-cladding layers on interfacial recombination and found that reducing the deep level concentration from 10 15 to 10 13 cm -3 reduces the interfacial recombination velocity from 140 to 60 cm/s and improves the radiative efficiency. Our results suggest that carriers in the active layer recombine nonradiatively at the interfaces due to the deep level in cladding layers.

Mg-doping transients during metalorgic vapor phase epitaxy of GaAs and AlGaInP

Abstract We studied magnesium-doping transients during metalorgic vapor phase epitaxy of GaAs and (Al x Ga 1- x ) 0.5 In 0.5 P (0 ⪯ x ⪯ 0.7). We examined the transient of Mg concentration depth profile through epitaxial layers when Mg precursors are initially injected into the reactor (doping delay). We found that increasing the Al composition of epitaxial layers, i.e., increasing the mole fraction of Al precursors in the reactor, significantly reduces the Mg-doping delay. We obtained this result for both trimethylaluminum (TMAl) and triethylaluminum (TEAl). We quantitatively modeled this phenomenon based on the competitive adsorption of Mg and Al precursors on the internal surface of the reactor. Our model also explains that the Mg concentration in epitaxial layers increases either linearly or superlinearly with the Mg precursor input, depending on the length of the doping delay.

MOVPE growth and optical properties of AlGaInP/GaInP strained single quantum well structures

Abstract AlGaInP/GaInP strained single quantum well (SSQW) structures have been grown by metalorganic vapor phase epitaxy. 4.2 K photoluminescence (PL) linewidth was as narrow as 9 to 13 meV for a well thickness of 10 nm and the misfit strain over ±1%, indicating excellent structural quality comparable to lattice-matched QWs. The structure of room temperature PL spectra was significantly affected by the misfit strain. Comparison with a theoretical calculation confirmed that the spectra arise from a mixture of optical transitions from the n =1 conduction subband to the n =1 heavy-hole and to the n =1 light-hole subband. The degree of the valence band degeneracy removal could be determined experimentally from the PL spectra.

High-quality InGaAsP/InP single-quantum wells and superlattice structures grown by low-pressure metalorganic vapor phase epitaxy

Abstract High-quality In 0.73 Ga 0.27 As 0.60 P 0.40 /InP single-quantum well (SQW) and multiple-quantum well (MQW) (or superlattice) structures have been successfully grown by low-pressure metalorganic vapor phase epitaxy (LP-MOVPE). 4 K photoluminescence (PL), optical absorption, spectroscopy, small-angle X-ray diffraction (SAXD), and high-resolution transmission electron microscopy (HRTEM) were used to characterize the QW structures. HRTEM lattice images suggested that the narrowest InGaAsP SQW can be a one-monolayer wide (3 A). A PL energy upshift as large as 325 meV and a PL linewidth as narrow as 14 meV were obtained for the narrowest well. SAXD and 4 K PL analyses confirmed the excellent uniformity of the composition and the layer thickness of each component of MQW structures along the growth directions. Well-defined excitonic resonance absorption peaks were also observed for MQW structures at 77 K.

X‐ray diffraction from ordered regions in GaInP ternary alloys

Ordered structure in GaInP alloys grown on (001) GaAs substrates by low‐pressure metalorganic vapor phase epitaxy has been investigated by means of x‐ray diffraction and transmission electron microscopy. We found a broad peak of CuPt I type (111)B ordering in the x‐ray measurements. X‐ray results gave the total amount of ordered region and the average size of each ordered domain. Room‐temperature photoluminescence peak energy anomalies were found to be related to the amount of the order phase.

Self-aligned bend waveguide (SBW) AlGaInP visible laser diode with small beam astigmatism

The self-aligned bend waveguide (SBW) AlGaInP visible laser developed produces an index guiding waveguide structure by the bend of the double heterolayers and offers a very small beam astigmatism. The laser was fabricated using two-step metalorganic vapor phase epitaxy (MOVPE). Kink-free operation at 40 mW was achieved by modifying the device parameters. The measured beam astigmatism was maintained at less than 1 mu m and did not vary with output power. The aging results under the condition of 50 degrees C and 20 mW output power demonstrated the lasers reliability. >