Uncooled InSb mid-infrared LED used dislocation filtering of AlInSb layer

Abstract

The uncooled InSb mid-infrared LED (Light Emitting Diode) using dislocation filtering of the AlInSb layer is reported. InSb is quite suitable as a material for optical devices in the mid-infrared (3–7μm) wavelength region. The structure of the InSb LED was grown on a semi-insulating GaAs (001) substrate by a Riber MBE-49 system. Because of the large lattice mismatch (14.6%) between an InSb and a GaAs substrate, there were many threading dislocations (TDs) in this structure. The density of the TDs in the p−-active layer was about 1.3×109 [cm−2]. We inserted five n+-Al0.17In0.83Sb (20nm) layers in the bottom n+-InSb layer of the LED. The first AlInSb layer was grown on the 0.5μm n+-InSb layer. In addition, 20nm n+-InSb layers were grown between each n+-Al0.17In0.83Sb layer. The n+-Al0.17In0.83Sb layer was then inserted into the interface of n+-InSb and p‐-InSb. The TDs were blocked by the AlInSb layers and the density in the p−-active layer was reduced to about 4.0×108 [cm−2]. Subsequently, we fabricated the circular LED of 500μm. The diodes were driven using a square waveform at 1kHz at a peak injection current of 100mA at 298K, and a duty cycle of 50%. The forward bias emission spectra of diodes were measured by a Fourier-transform infrared spectrometer. The peak emission occurred at 6.3μm and the intensity of the LED with AlInSb layers was 2.3 times greater than the LED without AlInSb layers. These results indicated that the structure of the LED with AlInSb layers was promising as a source of mid-infrared.