Abstract
The effects of composition and p-doping profile of the AlGaN:Mg electron blocking layer (EBL) in 310 nm ultraviolet B (UV-B) light emitting diodes (LEDs) have been investigated. The carrier injection and internal quantum efficiency of the LEDs were simulated and compared to electroluminescence measurements. The light output power depends strongly on the temporal biscyclopentadienylmagnesium (CpMg) carrier gas flow profile during growth as well as on the aluminum profile of the AlGaN:Mg EBL. The highest emission power has been found for an EBL with the highest CpMg carrier gas flow and a gradually decreasing aluminum content in direction to the p-side of the LED. This effect is attributed to an improved carrier injection and confinement that prevents electron leakage into the p-doped region of the LED with a simultaneously enhanced carrier injection into the active region.
Highlights
The effects of composition and p-doping profile of the AlGaN:Mg electron blocking layer (EBL) in 310 nm ultraviolet B (UV-B) light emitting diodes (LEDs) have been investigated
We report on the effects of different temporal Cp2 Mg carrier gas flow profiles during growth of the AlGaN:Mg EBL and different compositional designs of the EBL on the emission characteristics of 310 nm LEDs
The Cp2 Mg carrier gas flow was varied during the growth of the EBL
Summary
(In)AlGaN based LEDs in the UV-B spectral range are promising candidates that could replace established UV light sources in various applications, e.g., medical diagnostics, phototherapy, and plant growth lighting [1,2]. Composition [7], the number of QWs [8] and the QW width [9] on the emission characteristics of UV-B LEDs. The second key challenge to realize efficient UV-B LEDs is an efficient carrier injection. Systematic investigations of EBL designs have not yet been presented for UV-B LEDs. In this paper, we report on the effects of different temporal Cp2 Mg carrier gas flow profiles during growth of the AlGaN:Mg EBL and different compositional designs of the EBL on the emission characteristics of 310 nm LEDs. The results of electroluminescence measurements will be discussed in combination with simulations of the carrier injection into the (In)AlGaN multiple quantum well active region of the UV-B LEDs
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