Improvement of optical properties of gas source MBE grown GaPAlP short period superlattices

Optical properties of (GaP)m(AlP)n normal and (GaP)m1(AlP)n1(GaP)m2(AlP)n2(m = m1 + m2, n = n1 + n2, m1 ≥ m2, n1 ≥ n2) modulated superlattices (SLs) grown by gas source molecular beam epitaxy are studied. Optical properties of the normal SLs are improved with increasing growth temperature. The highest photoluminescence (PL) intensity and the narrowest full width at half maximum (9 meV) are obtained for 640°C growth. It is found that the PL intensity variation with measuring temperature is slower for the 640°C grown SLs than for the 600°C grown SLs. Modulated SLs show strong dependence of the PL intensity and wavelength on the modulated SL structure. The PL intensity of the (m1 + n1 = odd, m2 + n2 = odd) modulated SLs shows slower temperature variation than that of the normal SLs. At 30 K, the PL intensity of the (9, 4)(4, 3) modulated SL is 2500 times stronger than that of the (13, 7) normal SL. Electroluminescence (EL) emission was measured at 130–300 K for preliminary fabricated light emitting diodes having a GaPAlP (9, 4)(4, 3) modulated SL as the active layer. The temperature variations of PL and EL wavelengths confirm that the EL emission originates from the GaPAlP modulated SL active layer.