Diagram showing the layer structure of asymmetric p+/n diodes for DLTS measurements of n-type GaAs1−xBix layers. The arrows indicate where substrate temperature changes were made to achieve abrupt heterointerfaces between the GaAs and GaAsBi layers.
Band diagram of an n-type Schottky diode at zero applied voltage with the conduction band energy, EC , the donor energy, ED , the Fermi energy, EF , and a trap energy, ET , indicated. W is the depletion width and λ indicates the distance from the edge of the depletion region to the point, where ET = EF . Traps within the distance λ of the depletion edge at reverse bias do not contribute to the DLTS signal.
DLTS spectra for n-type GaAs layers grown at three different substrate temperatures as indicated. The emission rate is 1163 s−1. The trap filling pulse was 0.5 V forward bias for 2 ms. The steady state reverse bias voltage was 0.5 V for the layers grown at 580 °C and 390 °C and 0.2 V for the layer grown at 330 °C.
DLTS spectra for three GaAsBi layers grown at 330 °C having the Bi fraction indicated and the n-type GaAs layer grown at 390 °C. The emission rate is 1163 s−1. The trap filling pulse was 0.5 V forward bias for 2 ms. The steady state reverse bias voltage was 0.5 V for the GaAs layer. For the GaAsBi layers it was 2.5 V for 0.3%, 0.5 V for 0.7%, and 1.0 V for 1.1%.
Arrhenius plots comparing emission rates of traps in the GaAs sample grown at 390 °C and the three GaAsBi samples.
Growth temperature, Bi fraction, As/Ga atom ratio, growth rate, and net donor concentration of the n-type layer in samples prepared for DLTS measurements. All devices are asymmetric p+/n junction diodes except for the GaAs Schottky diode grown at 390 °C. The doping concentration is from capacitance-voltage measurements at 300 K.
Electron trap parameters from DLTS measurements. Parameters are averages of the values measured for several diodes on each sample. The error in the activation energy is typically ±0.02 eV and about an order of magnitude for the capture cross section.
Article metrics loading...
Full text loading...