Relaxed InAsP layers grown on step graded InAsP buffers by solid source MBE

Abstract

Si-doped InAsxP1-x layers with As mole fractions ranging from 0.05 to 0.50 were grown on InAsxP1-x step-graded buffer layers on InP substrates by solid source molecular beam epitaxy. The growth parameters consisted of a P:In flux ratio of 7:1, a growth temperature of ∼ 485°C, a growth rate of 2.2 Å/s, and an As:In flux ratio of 0.37-2.36 for varying As mole fractions. The As mole fraction and the layer relaxation were determined using triple axis x-ray diffraction measurements. Near complete relaxation (>93%) was achieved for all Si-doped InAsxP1-x epilayers. The structural morphology indicated that the InAsxP1-x graded buffer layers were effective in relieving the lattice mismatch strain as evidenced by a well-developed crosshatch morphology and low rms surface roughness. The electron concentration, mobility, and Si donor activation energy for each InAsxP1-x composition were determined using temperature dependent Hall measurements. At a constant electron carrier concentration of %3.5×1016 cm-3, the 300 K carrier mobility increased from 2700 to 4732 cm2/V-sec with increasing As mole fraction from 0.05 to 0.50.

Effect of epilayer's growth temperature on crystalline quality of InAs0.6P0.4/InP grown by two-step growth method

“…It is obvious that the changes of carrier concentration and mobility are related to epilayer's growth temperature. In the epilayers, the residual misfit dislocations in epilayers act as scattering centers and reduce the carrier mobility [15,16]. Defects of the InAs 0.6 P 0.4 epilayer are decreased by optimizing the epilayer's growth temperatures.…”

Step-graded InAsP buffer layers with gradient interface grown via metal organic chemical vapor deposition

“…There are several growth options for the buffer layers, such as the step-graded buffer layers [11][12][13], lineargraded buffer layers [14], two-/multi-step low-temperature buffer layers [15,16], and superlattice buffer layers [17]. Linear-graded buffer layers are commonly used in metalorganic chemical vapor deposition (MOCVD) growth of the buffer layers: By linearly adjusting the source flow rate with the mass flow controller (MFC), the material composition of the buffer layer can be easily changed from the substrate to the desired composition of the epitaxial layer.…”