Temperature dependent admittance spectroscopy of GaAs/AlGaAs single-quantum-well laser diodes (SQWLDs)

In this study, the main electrical parameters, such as doping concentration (ND), barrier height (ΦCV), depletion layer width (WD), series resistance (Rs) and Fermi energy level (EF), of GaAs/AlxGa1−xAs single quantum well (SQW) laser diodes were investigated using the admittance spectroscopy (C–V and G/ω–V) method in the temperature range of 80–360 K. The reverse bias C−2 vs. V plots gives a straight line in a wide voltage region, especially in weak inversion region. The values of ΦCV at the absolute temperature (T = 0 K) and the temperature coefficient (α) of barrier height were found as 1.22 eV and −8.65 × 10−4 eV/K, respectively. This value of α is in a close agreement with α of GaAs band gap (−5.45 × 10−4 eV/K). Experimental results show that the capacitance–voltage (C–V) and conductance–voltage (G/ω–V) characteristics of the diode are affected by not only temperature but also Rs. The capacitance–voltage–temperature (C–V–T) and conductance–voltage–temperature (G/ω–V–T) characteristics confirmed that temperature and Rs of the diode have effects on the electronic parameters in SQW laser diodes.

Research highlights▶ It is well known the quantum-well (QW) lasers are the most important optoelectronic devices in many application fields. The temperature dependent I–V and C–V measurements allow us to understand the different aspects of conduction mechanisms of these devices. The C–V and G/ω–V measurements should be done over a wide range of temperature in order to have a better understanding of the nature of barrier height and conduction mechanisms. Therefore, in this study, the main electrical parameters of GaAs/AlxGa1−xAs single quantum well (SQW) laser diodes were determined from the admittance spectroscopy C–V and G/ω–V method in the temperature range of 80–360 K. In addition, the capacitance and conductance values measured under both reverse and forward bias were corrected in order to eliminate the effect of Rs to obtain the real diode capacitance.