We report successful growth of antiphase domain‐free InP on Si(001) without any preannealing of the Si substrate using low‐pressure metalorganic chemical vapor deposition in contrast to present belief that high‐temperature substrate annealing prior to growth is imperative to achieve this goal. Optimized crystallographic and optical properties are obtained for an offcut along [110] of 4°±0.4°, an InP buffer layer temperature of 400 °C±10 °C, a layer deposition temperature of 640 °C, and low growth rates r≤2.7 μm/h.

Low‐temperature metalorganic chemical vapor deposition of InP on Si(001)

Growth and characterization of InP on silicon by MOCVD

The effects of hydrogenation on the properties of Zn‐doped InP/GaAs heterostructures grown by metalorganic chemical vapor deposition were studied by current‐voltage (I‐V), deep level transient spectroscopy (DLTS), and photoluminescence. Significant improvements in leakage current and breakdown voltage in InP diodes on GaAs were observed after a 2 h hydrogen plasma exposure at 250 °C. DLTS indicated a corresponding reduction in total trap concentration from ∼6×1014 to ∼3×1012 cm−3 at a depth of ∼1.5 μm below the surface. The Zn dopants were completely reactivated by a subsequent 5 min 400 °C anneal without degradation of the reverse current or reactivation of the deep levels. Anneals in excess of 580 °C were necessary to reactivate the deep levels and degrade the leakage current to their original values, indicating the passivation of threading dislocations by hydrogen, and the existence of a wide temperature window for post‐passivation processing.

Hydrogen passivation of dislocations in InP on GaAs heterostructures

Relaxed lattice-mismatched growth of III–V semiconductors

In previous work we reported on the stable passivation of dislocations in InP/GaAs heterostructures by plasma hydrogenation (Chatterjee et al., Appl. Phys. Lett. vol. 65, p. 58, 1994). In this article we investigate and compare the trapping kinetics and general trapping properties of dislocations in strain relaxed p‐InP grown on GaAs by metalorganic chemical vapor deposition prior to and after hydrogen passivation using deep level transient spectroscopy (DLTS) and current‐voltage‐temperature (I‐V/T) measurements to determine the complete role of hydrogen passivation in these heterostructures. Three hole traps, T1A, T1B, and T2, were detected and attributed to dislocations in heteroepitaxial p‐InP which displayed the logarithmic capture kinetics, extended dependence on fill pulse time, and broadened DLTS features expected for dislocation related traps. Quantitative analysis of the DLTS characteristics revealed progressive asymmetry in DLTS peak shape, an increase in characteristic peak width, and a decrease in activation energy as fill pulse time is increased until saturation values were reached.These observations are explained on the basis of a distribution or band of energy states for each trap resulting from the interaction of electrically active sites either between closely spaced dislocations or along dislocation cores within the strain‐relaxed InP. For fill pulse times increasing from 1 μs to 10 ms, activation energies for T1A decreased monotonically from 0.80 to 0.65 eV, for T1B from 0.56 to 0.45 eV, and for T2 from 0.45 to 0.35 eV, with saturation occurring at the upper and lower limits for each trap, which indicates a qualitative measure of the energy spread for each trap. Plasma hydrogenation was not only found to passivate dislocations by reducing the trap concentration from ∼6×1014 to ∼3×1012 cm−3 for a 2 h exposure, but also strikingly altered their basic trapping properties. The qualitative measure of energy spread for the T1A and T2 traps were narrowed from ∼100 to 150 meV to ∼20 to 30 meV after a 2 h hydrogen exposure, whereas T1B was not detected after passivation. In addition, a simultaneous reduction in fill pulse saturation time, DLTS peak broadening, and peak shift as a function of hydrogen exposure time were observed. These observations suggest that hydrogen passivation modifies the dislocation trapping characteristics toward a more point defectlike behavior due to an increase in the average spacing between electrically active dislocation sites. This in turn reduces the interactions between these sites and narrows the distribution of states within each defect band. Further, reverse bias I‐V/T measurements revealed that the near midgap trap T1A, which was found to dominate the space charge generation current prior to passivation, is no longer dominant after hydrogen passivation. Instead a 2 h hydrogen treatment shifted the dominant center to an activation energy which more closely matches the shallow T2 level.

Hydrogen passivation and its effects on carrier trapping by dislocations in InP/GaAs heterostructures

The thickness dependence of material quality of InP‐GaAs‐Si structures grown by atmospheric pressure metalorganic chemical vapor deposition was investigated. The InP thickness was varied from 1–4 μm, and that of the GaAs from 0.1–4 μm. For a given thickness of InP, its ion channeling yield and x‐ray peak width were essentially independent of the GaAs layer thickness. The InP x‐ray peak widths were typically 400–440 arcsec for 4‐μm‐thick layers grown on GaAs. The GaAs x‐ray widths in turn varied from 320–1000 arcsec for layer thicknesses from 0.1–4 μm. Cross‐sectional transmission electron microscopy showed high defect densities at both the InP‐GaAs and GaAs‐Si interfaces. In 4‐μm‐thick InP layers the average threading dislocation density was in the range (3–8)×108 cm−2 with a stacking fault density within the range (0.4–2)×108 cm2. The He+ ion channeling yield near the InP surface was similar to that of bulk InP (χmin∼4%), but rose rapidly toward the InP‐GaAs heterointerface where it was typically around ...

M. M. Al‐Jassim

Papers

Characterization of InP/GaAs/Si structures grown by atmospheric pressure metalorganic chemical vapor deposition