Current blocking structure to improve semiconductor laser performance

Abstract

The layer structure of a DC-PBH laser diode consists of an n-InP substrate ( ), an n-InP buffer layer ( ), an undoped-InGaAsP active layer ( ), a p-Inp cladding layer ( ), a p-InP current blocking layer ( ), an n-InP current blocking layer ( ), a p-InP cladding layer ( ), and a p-InGaAsP contact layer ( ). An additional layer of Fe-doped InP layer ( ) creates an acceptor level (Fe /Fe ) near mid-band gap. The iron impurities are deep level traps, and will make the capacitance C less dependent of the impurity concentration of layer ( ) which is normally doped with a concentration larger than 1×10 cm to lower the leakage current from p-InP blocking layer ( ) to p-InP blocking layer ( ) that does not contribute to light emission. The capacitance C and hence the overall capacitance C will be reduced with this Fe doped InP layer ( ) and consequently the displacement current through the current blocking structure during high speed operation will be lowered. In addition, as this Fe-doped InP layer is also a thermally stable semi-insulating material, a high resistivity layer is thus formed between the n-InP blocking layer ( ) and P-InP blocking layer ( ). Thus, this Fe doped InP layer ( ) will also effectively reduce the leakage current flowing through the p-n-p-n current blocking channel as mentioned above.