Deep levels in In0.53Ga0.47 As/InP heterostructures

Abstract

We report on deep levels in In_0.53Ga_0.47 As/InP heterostructure avalanche photodiodes grown by liquid‐phase epitaxy. Two electron levels have been identified and studied using both admittance spectroscopy and a static capacitance‐voltage technique. One level, found only in the InP layer, is acceptor‐like with an activation energy of ε_tA = 0.20±0.02 eV and has a density in the bulk of the InP layer of N_tA≊ 10¹⁵ cm⁻³. The density of the trap increases sharply at the In_0.53Ga_0.47 As/InP heterointerface to a value nearly ten times the background carrier concentration in this region. Filling of this trap at low temperatures reduces the conduction band discontinuity at the heterointerface from Δε_c = 0.19 to 0.03 eV due to repulsion of the bands. The second trap, which is characteristic only of the In_0.53Ga_0.47 As, has an activation energy of ε_tB = 0.16±0.01 eV, and a density of between 3×10¹³ and 8×10¹³ cm⁻³.