Excitonic photoluminescence in high-purity InAs MBE epilayers on GaAs substrates

Abstract

Temperature-and excitation-dependent photoluminescence measurements have been carried out on 0.7-5 um thick heteroepitaxial InAs layers grown by molecular beam epitaxy (MBE). Excitonic photoluminescence with linewidths down to 5 meV reveals t h e high optical quality of t h e epilayers despite t h e 7",,, mismatch between the lnAs and the GaAs substrates. Peaks at 403 and 391 meV, which quench rapidly with increasing temperature, are attributed to bound excitons, and a sharp (7 meV FWHM) intense line at 417 meV is tentatively attributed to free excitonic recombination. A broad 18 meV wide band (peaking at 378 meV) which blue shifts with increasing excitation. characteristic of a donor-acceptor pair transition band, is reported for the first time in InAs.

Photoluminescence of chemically treated InAs (111)A

“…However B-B transitions were reported by Lacroix et al [12] at around 0.415 eV (at 1.4 K) for InAs grown by metal organic chemical vapour deposition (MOCVD). The free exciton transition has also been reported by Tang et al [13] for MBE grown InAs at around 0.417 eV (at 11 K). Two impurity-related transitions, a shallow and a deep donor bound exciton at 0.414 eV [13] and 0.403 eV [14], respectively, have been observed for MOCVD-grown (n ~510 15 cm -3 ) and MBE-grown (n ~510 14 cm -3 ) n-InAs.…”

“…The free exciton transition has also been reported by Tang et al [13] for MBE grown InAs at around 0.417 eV (at 11 K). Two impurity-related transitions, a shallow and a deep donor bound exciton at 0.414 eV [13] and 0.403 eV [14], respectively, have been observed for MOCVD-grown (n ~510 15 cm -3 ) and MBE-grown (n ~510 14 cm -3 ) n-InAs. Note that the formation of excitons typically occurs for free electron concentrations below the Mott screening density (~510 14 cm -3 ) [15].…”

“…This transition was observed for the first time by Fang et al [14] and later by Tang et al [13]. Both groups assigned this line to an exciton bound to a deep donor, suggested by Wang et al to be carbon [8].…”

InAs0.7Sb0.3 Bulk Photodiodes Operating at Thermoelectric‐Cooler Temperatures

“…For example, barrier detector current responsivity at small bias usually approaches zero; as a result, normally, the figure of merit is the dark current at a curtain bias and not the value of R o A . The 233 K dark current value J dark in our PDs was several times smaller than that in InAsSb 0.4 barrier photodiodes at U = −0.45 V with similar spectral response and was ≈10 times higher than the values derived from the “Rule 07” directives . Shown in Figure is the temperature dependence of the J dark /T 3 ratio at biases of −0.1 and −0.4 V, where the term T 3 accounts for the temperature dependence of the density of states in the expression for the diffusion current density .…”

“…). For InAsSb‐based structures, the above property is believed to be enabled by their unique property of producing electronic states above the conduction band, thereby suppressing the Shockley–Read–Hall recombination processes . There is thus a good chance for manufacturing efficient PDs for radiation detection at wavelengths exceeding 6 µm by using lattice mismatched substrates, e.g., InAs substrates for the InAs 1− x Sb x /InAs ( x > 0.2, Δa/a > 0.015) heterostructure PDs.…”