S. A. Schwarz

Orientation dependence of S,Zn,Si,Te and Sn doping in OMCVD growth of InP and GaAs : application to DH lasers and lateral p-n junction arrays grown on non-planar substrates

Abstract The orientation dependence of doping in organometallic chemical vapor deposition (OMCVD) is shown to be far more complex than previously believed, with the variation of doping with increasing misorientation from (100) towards the (111)A/B being non-monotonic. However, the ratio of the n-doping on the B face to that on the corresponding A face is always greater than 1, irrespective of whether the dopant is a group IV or VI element. For p-doping with Zn, the reverse is true. The orientation dependence of doping has been used to create current blocking layers in InP/InGaAsP double heterostructure (DH) and multiple quantum well (MQW) lasers grown in a single step on a mesa or in a V-groove.

GROWTH OF HIGH QUALITY ALINAS BY LOW PRESSURE ORGANOMETALLIC CHEMICAL VAPOR DEPOSITION FOR HIGH SPEED AND OPTOELECTRONIC DEVICE APPLICATIONS

In this paper, we report on the low pressure organometallic chemical vapor deposition of AlInAs lattice matched to InP and the effect of the substrate temperature and V/III ratio on the layers grown. High quality AlInAs with X-ray and photoluminescence (5 K) linewidths of 21 arc sec and 15 meV, respectively, was obtained. It is demonstrated that a high growth temperature and a high arsine flow rate are necessary for obtaining good electrical and optical properties. A discrepancy was shown to exist between C-V and Hall derived carrier concentrations probably due to deep levels affecting the C-V measurements and a two-dimensional electron gas (2DEG) at the AlInAs/InP interface affecting the Hall measurements. The existence of a 2DEG at the AlInAs/InP interface, with a sheet density of 2.9×1011 cm-2 and a mobility of 11050 cm2/V°s at 4 K, was shown using Shubnikov-De Haas measurements. A correlation was made between oxygen or an oxygen related complex and high C-V measured carrier concentrations and large leakage currents in reverse biased Schottky contacts. An intense emission at ~1.2 eV, present in 5 K photoluminescence spectra of AlInAs/InP, was attributed to a spatially indirect transition across the AlInAs/InP interface. Conduction and valence band offsets of 448.8 and 324.3 meV, respectively, were deduced from the energy of this transition. Self aligned 0.25 μm gate high electron mobility AlInAs/GaInAs transistors with a transconductance as high as 1150 mS/mm and ft = 80 GHz at room temperature were fabricated. Finally, metal-semiconductor-metal photodetectors with a leakage current as low as 5 nA at 5 V, breakdown voltage greater than 25 V, responsivity of 0.42 A/W at 1.3 μm wavelength, and a bandwidth of 8 GHz were demonstrated.

Comparative studies of ion‐induced mixing of GaAs‐AlAs superlattices

The species dependence of ion‐induced superlattice mixing has been examined in AlAs‐GaAs superlattice samples grown by molecular beam epitaxy. The interdiffusion of the superlattices induced by ion implantation with comparable ranges, doses, and subsequent thermal anneals were measured with secondary ion mass spectrometry. The effects of elements of comparable mass (Ga, As, and Ge) and comparable valence (Si and Ge) were studied. The experimental results show that Ga and As implantation cause primarily collision‐induced mixing, while Ge implantation results in collision‐induced mixing with additional impurity‐induced mixing beyond the implant range. In comparison with Ge, Si‐induced mixing is similar in nature though there is significant difference in the depth and extent of the mixing. The extent of mixing is found to depend on the local Ge or Si concentration.

Optically monitoring and controlling epitaxial growth

Abstract We provide a perspective on current capabilities for optically monitoring and controlling epitaxial growth, and discuss examples taken from recent work at Bellcore.

Arsenic doped ZnSe grown by molecular‐beam epitaxy

We have been able to incorporate As into molecular‐beam epitaxy (MBE) grown ZnSe in the range of 1017–1021 atoms/cm3 using Zn3As2 as the As source. This contrasts with very low As levels we obtained using an As cracker cell. The As incorporation is highly nonlinear with Zn3As2 flux and depends on the excess Se used. Several samples doped with Zn3As2 show low temperature photoluminescence with near band edge emission dominated by shallow acceptor levels. We will describe the details of several growth variations studied and their influence on As incorporation.

Orientation‐dependent doping in organometallic chemical vapor deposition on nonplanar InP substrates: Application to double‐heterostructure lasers and lateral p‐n junction arrays

In this letter we show that the orientation dependence of dopant incorporation can be used to obtain lateral patterning of doping by growing on nonplanar substrates. Specifically, organometallic chemical vapor deposition has been used to obtain lateral p‐n junction arrays and selective deposition of alternating p‐n layers of InP. The latter technique has been used to grow double‐heterostructure lasers with current confinement layers in a single step.

A novel technique for the preservation of gratings in InP and InGAAsP and for the simultaneous preservation of InP, InGaAs, and InGaAsP in OMCVD

Regrowth steps in the fabrication of optoelectronic devices often require simultaneous preservation of InP, InGaAs, and InGaAsP during the initial heat-up before growth. In addition, if a grating is present on the wafer surface, it is necessary to prevent mass transport from eliminating it. We report on the use of As4 and P4 vapors to preserve gratings in InP and InGaAsP and also simultaneously preserve InP, InGaAs, and InGaAsP. Thermodynamic calculations are used to show that at 625°C InP and InGaAs are stable in As4 and P4 but not in AsH3 and PH3, respectively. The preservation technique developed in this study was used to fabricate high performance multiple quantum well planar buried heterostructure lasers and travelling wave amplifiers.

As capture and the growth of ultrathin InAs layers on InP

Capture of As by (001) InP surfaces exposed to As fluxes under chemical beam epitaxy conditions is investigated by virtual‐interface analysis of real‐time kinetic ellipsometric data. Intentional growth of ultrathin InAs layers is readily followed. Arsenic accumulated in the absence of growth can be completely removed by exposure to P, showing that As‐P exchange occurs only in the outermost layer.

Evidence for heavy ion channeling in AlGaAs at low energies

We used a new molecular dynamics simulation program to model the scattering of low‐energy ions into the relatively open 〈011〉 axial channels of zinc‐blende crystals. We also implanted 1–5 keV Si ions into GaAs/AlGaAs multiple‐quantum well samples and used secondary ion mass spectrometry and photoluminescence to search for the deep ion penetration and optical damage which are characteristic of this ion channeling. Both the simulated and measured Si depth distributions have exponential tails extending at least 20 times further than the mean ion range. The photoluminescence efficiencies are severely degraded in the quantum wells which are overlapped by the observed Si profile tails. These results suggest that unintentional ion channeling is a major factor in the extensive degradation of optical and electrical properties of semiconductor surfaces which are exposed to low‐energy ion bombardment during device fabrication.

Roughness at the interface of thin InP/InAs quantum wells

We investigated the interface roughness of InP/As quantum wells using photoluminescence and secondary ion mass spectroscopy. Typical photoluminescence spectra consist of multiple lines. The energies of the observed peaks have a remarkable behavior; namely, both the peak energies and the separations between peaks change from sample to sample. We discuss the interpretation of the observed emission lines in connection with questions such as interface roughness, island formation and lateral confinement. We also discuss the strong influence of parameters such as the growth temperature and the substrate orientation on the interface roughness.